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Enabling WDS #461

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kdave pushed a commit to kdave/btrfs-devel that referenced this pull request Feb 13, 2019
This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
kdave pushed a commit to kdave/btrfs-devel that referenced this pull request Feb 18, 2019
This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
kdave pushed a commit to kdave/btrfs-devel that referenced this pull request Feb 25, 2019
This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
damentz pushed a commit to zen-kernel/zen-kernel that referenced this pull request Mar 23, 2019
commit 1cec3f2 upstream.

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
jackpot51 pushed a commit to pop-os/linux that referenced this pull request May 3, 2019
BugLink: https://bugs.launchpad.net/bugs/1821607

commit 1cec3f2 upstream.

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
mrchapp pushed a commit to mrchapp/linux that referenced this pull request Sep 12, 2019
[ Upstream commit 1cec3f2 ]

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
mrchapp pushed a commit to mrchapp/linux that referenced this pull request Sep 13, 2019
[ Upstream commit 1cec3f2 ]

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Noltari pushed a commit to Noltari/linux that referenced this pull request Sep 16, 2019
[ Upstream commit 1cec3f2 ]

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
mrchapp pushed a commit to mrchapp/linux that referenced this pull request Sep 16, 2019
[ Upstream commit 1cec3f2 ]

This fixes a longstanding lockdep warning triggered by
fstests/btrfs/011.

Circular locking dependency check reports warning[1], that's because the
btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock
held. The test case leading to this warning:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /btrfs
  $ btrfs scrub start -B /btrfs

In fact we have fs_info::scrub_workers_refcnt to track if the init and destroy
of the scrub workers are needed. So once we have incremented and decremented
the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the
scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this
patch drops the scrub_lock before calling btrfs_destroy_workqueue().

  [359.258534] ======================================================
  [359.260305] WARNING: possible circular locking dependency detected
  [359.261938] 5.0.0-rc6-default torvalds#461 Not tainted
  [359.263135] ------------------------------------------------------
  [359.264672] btrfs/20975 is trying to acquire lock:
  [359.265927] 00000000d4d32bea ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x87/0x540
  [359.268416]
  [359.268416] but task is already holding lock:
  [359.270061] 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.272418]
  [359.272418] which lock already depends on the new lock.
  [359.272418]
  [359.274692]
  [359.274692] the existing dependency chain (in reverse order) is:
  [359.276671]
  [359.276671] -> #3 (&fs_info->scrub_lock){+.+.}:
  [359.278187]        __mutex_lock+0x86/0x9c0
  [359.279086]        btrfs_scrub_pause+0x31/0x100 [btrfs]
  [359.280421]        btrfs_commit_transaction+0x1e4/0x9e0 [btrfs]
  [359.281931]        close_ctree+0x30b/0x350 [btrfs]
  [359.283208]        generic_shutdown_super+0x64/0x100
  [359.284516]        kill_anon_super+0x14/0x30
  [359.285658]        btrfs_kill_super+0x12/0xa0 [btrfs]
  [359.286964]        deactivate_locked_super+0x29/0x60
  [359.288242]        cleanup_mnt+0x3b/0x70
  [359.289310]        task_work_run+0x98/0xc0
  [359.290428]        exit_to_usermode_loop+0x83/0x90
  [359.291445]        do_syscall_64+0x15b/0x180
  [359.292598]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.294011]
  [359.294011] -> #2 (sb_internal#2){.+.+}:
  [359.295432]        __sb_start_write+0x113/0x1d0
  [359.296394]        start_transaction+0x369/0x500 [btrfs]
  [359.297471]        btrfs_finish_ordered_io+0x2aa/0x7c0 [btrfs]
  [359.298629]        normal_work_helper+0xcd/0x530 [btrfs]
  [359.299698]        process_one_work+0x246/0x610
  [359.300898]        worker_thread+0x3c/0x390
  [359.302020]        kthread+0x116/0x130
  [359.303053]        ret_from_fork+0x24/0x30
  [359.304152]
  [359.304152] -> #1 ((work_completion)(&work->normal_work)){+.+.}:
  [359.306100]        process_one_work+0x21f/0x610
  [359.307302]        worker_thread+0x3c/0x390
  [359.308465]        kthread+0x116/0x130
  [359.309357]        ret_from_fork+0x24/0x30
  [359.310229]
  [359.310229] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}:
  [359.311812]        lock_acquire+0x90/0x180
  [359.312929]        flush_workqueue+0xaa/0x540
  [359.313845]        drain_workqueue+0xa1/0x180
  [359.314761]        destroy_workqueue+0x17/0x240
  [359.315754]        btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.317245]        scrub_workers_put+0x2c/0x60 [btrfs]
  [359.318585]        btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.319944]        btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.321622]        btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.322908]        do_vfs_ioctl+0xa2/0x6d0
  [359.324021]        ksys_ioctl+0x3a/0x70
  [359.325066]        __x64_sys_ioctl+0x16/0x20
  [359.326236]        do_syscall_64+0x54/0x180
  [359.327379]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.328772]
  [359.328772] other info that might help us debug this:
  [359.328772]
  [359.330990] Chain exists of:
  [359.330990]   (wq_completion)"%s-%s""btrfs", name --> sb_internal#2 --> &fs_info->scrub_lock
  [359.330990]
  [359.334376]  Possible unsafe locking scenario:
  [359.334376]
  [359.336020]        CPU0                    CPU1
  [359.337070]        ----                    ----
  [359.337821]   lock(&fs_info->scrub_lock);
  [359.338506]                                lock(sb_internal#2);
  [359.339506]                                lock(&fs_info->scrub_lock);
  [359.341461]   lock((wq_completion)"%s-%s""btrfs", name);
  [359.342437]
  [359.342437]  *** DEADLOCK ***
  [359.342437]
  [359.343745] 1 lock held by btrfs/20975:
  [359.344788]  #0: 0000000053ea26a6 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x322/0x590 [btrfs]
  [359.346778]
  [359.346778] stack backtrace:
  [359.347897] CPU: 0 PID: 20975 Comm: btrfs Not tainted 5.0.0-rc6-default torvalds#461
  [359.348983] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014
  [359.350501] Call Trace:
  [359.350931]  dump_stack+0x67/0x90
  [359.351676]  print_circular_bug.isra.37.cold.56+0x15c/0x195
  [359.353569]  check_prev_add.constprop.44+0x4f9/0x750
  [359.354849]  ? check_prev_add.constprop.44+0x286/0x750
  [359.356505]  __lock_acquire+0xb84/0xf10
  [359.357505]  lock_acquire+0x90/0x180
  [359.358271]  ? flush_workqueue+0x87/0x540
  [359.359098]  flush_workqueue+0xaa/0x540
  [359.359912]  ? flush_workqueue+0x87/0x540
  [359.360740]  ? drain_workqueue+0x1e/0x180
  [359.361565]  ? drain_workqueue+0xa1/0x180
  [359.362391]  drain_workqueue+0xa1/0x180
  [359.363193]  destroy_workqueue+0x17/0x240
  [359.364539]  btrfs_destroy_workqueue+0x57/0x200 [btrfs]
  [359.365673]  scrub_workers_put+0x2c/0x60 [btrfs]
  [359.366618]  btrfs_scrub_dev+0x336/0x590 [btrfs]
  [359.367594]  ? start_transaction+0xa1/0x500 [btrfs]
  [359.368679]  btrfs_dev_replace_by_ioctl.cold.19+0x179/0x1bb [btrfs]
  [359.369545]  btrfs_ioctl+0x28a4/0x2e40 [btrfs]
  [359.370186]  ? __lock_acquire+0x263/0xf10
  [359.370777]  ? kvm_clock_read+0x14/0x30
  [359.371392]  ? kvm_sched_clock_read+0x5/0x10
  [359.372248]  ? sched_clock+0x5/0x10
  [359.372786]  ? sched_clock_cpu+0xc/0xc0
  [359.373662]  ? do_vfs_ioctl+0xa2/0x6d0
  [359.374552]  do_vfs_ioctl+0xa2/0x6d0
  [359.375378]  ? do_sigaction+0xff/0x250
  [359.376233]  ksys_ioctl+0x3a/0x70
  [359.376954]  __x64_sys_ioctl+0x16/0x20
  [359.377772]  do_syscall_64+0x54/0x180
  [359.378841]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [359.380422] RIP: 0033:0x7f5429296a97

Backporting to older kernels: scrub_nocow_workers must be freed the same
way as the others.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ojeda added a commit to ojeda/linux that referenced this pull request Jul 29, 2021
rust: add a power management module.
fengguang pushed a commit to 0day-ci/linux that referenced this pull request Feb 15, 2022
ZONE_MOVABLE uses the remaining memory in each node. It's starting pfn
is also aligned to MAX_ORDER_NR_PAGES. It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is
not enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for. This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents
the maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages. In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available. This is used by iterators such as
walk_zones_in_node(). pagetypeinfo_showfree() uses this to walk the
free_list of each zone in each node, which are assumed to be initialised
due to the zone not being empty. As free_area_init_core() never
initialised the free_lists[] this results in the following kernel crash
when trying to read /proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Feb 16, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Feb 24, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Feb 25, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Feb 26, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Feb 28, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Mar 1, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Mar 3, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Mar 4, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
roxell pushed a commit to roxell/linux that referenced this pull request Mar 7, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Mar 10, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
jonhunter pushed a commit to jonhunter/linux that referenced this pull request Mar 17, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
roxell pushed a commit to roxell/linux that referenced this pull request Mar 18, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
torvalds pushed a commit that referenced this pull request Mar 22, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn
is also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is
not enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents
the maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as
walk_zones_in_node().  pagetypeinfo_showfree() uses this to walk the
free_list of each zone in each node, which are assumed to be initialised
due to the zone not being empty.

As free_area_init_core() never initialised the free_lists[] this results
in the following kernel crash when trying to read /proc/pagetypeinfo:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
  CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 #461
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
  RIP: 0010:pagetypeinfo_show+0x163/0x460
  Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
  RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
  RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
  RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
  RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
  R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
  R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
  FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
  Call Trace:
   seq_read_iter+0x128/0x460
   proc_reg_read_iter+0x51/0x80
   new_sync_read+0x113/0x1a0
   vfs_read+0x136/0x1d0
   ksys_read+0x70/0xf0
   __x64_sys_read+0x1a/0x20
   do_syscall_64+0x3b/0xc0
   entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Mar 25, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
intel-lab-lkp pushed a commit to intel-lab-lkp/linux that referenced this pull request Mar 25, 2022
ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn is
also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not
enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents the
maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as walk_zones_in_node().
pagetypeinfo_showfree() uses this to walk the free_list of each zone in
each node, which are assumed to be initialised due to the zone not being
empty.  As free_area_init_core() never initialised the free_lists[] this
results in the following kernel crash when trying to read
/proc/pagetypeinfo:

[   67.534914] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   67.535429] #PF: supervisor read access in kernel mode
[   67.535789] #PF: error_code(0x0000) - not-present page
[   67.536128] PGD 0 P4D 0
[   67.536305] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
[   67.536696] CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
[   67.537096] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[   67.537638] RIP: 0010:pagetypeinfo_show+0x163/0x460
[   67.537992] Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
[   67.538259] RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
[   67.538259] RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
[   67.538259] RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
[   67.538259] RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
[   67.538259] R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
[   67.538259] R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
[   67.538259] FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
[   67.538259] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   67.538259] CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
[   67.538259] Call Trace:
[   67.538259]  <TASK>
[   67.538259]  seq_read_iter+0x128/0x460
[   67.538259]  ? aa_file_perm+0x1af/0x5f0
[   67.538259]  proc_reg_read_iter+0x51/0x80
[   67.538259]  ? lock_is_held_type+0xea/0x140
[   67.538259]  new_sync_read+0x113/0x1a0
[   67.538259]  vfs_read+0x136/0x1d0
[   67.538259]  ksys_read+0x70/0xf0
[   67.538259]  __x64_sys_read+0x1a/0x20
[   67.538259]  do_syscall_64+0x3b/0xc0
[   67.538259]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   67.538259] RIP: 0033:0x7f9c83e23cce
[   67.538259] Code: c0 e9 b6 fe ff ff 50 48 8d 3d 6e 13 0a 00 e8 c9 e3 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   67.538259] RSP: 002b:00007fff116e1a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   67.538259] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f9c83e23cce
[   67.538259] RDX: 0000000000020000 RSI: 00007f9c83a2c000 RDI: 0000000000000003
[   67.538259] RBP: 00007f9c83a2c000 R08: 00007f9c83a2b010 R09: 0000000000000000
[   67.538259] R10: 00007f9c83f2d7d0 R11: 0000000000000246 R12: 0000000000000000
[   67.538259] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[   67.538259]  </TASK>

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 1, 2022
commit ddbc84f upstream.

ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn
is also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is
not enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents
the maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as
walk_zones_in_node().  pagetypeinfo_showfree() uses this to walk the
free_list of each zone in each node, which are assumed to be initialised
due to the zone not being empty.

As free_area_init_core() never initialised the free_lists[] this results
in the following kernel crash when trying to read /proc/pagetypeinfo:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
  CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
  RIP: 0010:pagetypeinfo_show+0x163/0x460
  Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
  RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
  RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
  RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
  RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
  R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
  R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
  FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
  Call Trace:
   seq_read_iter+0x128/0x460
   proc_reg_read_iter+0x51/0x80
   new_sync_read+0x113/0x1a0
   vfs_read+0x136/0x1d0
   ksys_read+0x70/0xf0
   __x64_sys_read+0x1a/0x20
   do_syscall_64+0x3b/0xc0
   entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 1, 2022
commit ddbc84f upstream.

ZONE_MOVABLE uses the remaining memory in each node.  Its starting pfn
is also aligned to MAX_ORDER_NR_PAGES.  It is possible for the remaining
memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is
not enough room for ZONE_MOVABLE on that node.

Unfortunately this condition is not checked for.  This leads to
zone_movable_pfn[] getting set to a pfn greater than the last pfn in a
node.

calculate_node_totalpages() then sets zone->present_pages to be greater
than zone->spanned_pages which is invalid, as spanned_pages represents
the maximum number of pages in a zone assuming no holes.

Subsequently it is possible free_area_init_core() will observe a zone of
size zero with present pages.  In this case it will skip setting up the
zone, including the initialisation of free_lists[].

However populated_zone() checks zone->present_pages to see if a zone has
memory available.  This is used by iterators such as
walk_zones_in_node().  pagetypeinfo_showfree() uses this to walk the
free_list of each zone in each node, which are assumed to be initialised
due to the zone not being empty.

As free_area_init_core() never initialised the free_lists[] this results
in the following kernel crash when trying to read /proc/pagetypeinfo:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
  CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 torvalds#461
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
  RIP: 0010:pagetypeinfo_show+0x163/0x460
  Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82
  RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003
  RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001
  RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b
  RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e
  R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00
  R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000
  FS:  00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0
  Call Trace:
   seq_read_iter+0x128/0x460
   proc_reg_read_iter+0x51/0x80
   new_sync_read+0x113/0x1a0
   vfs_read+0x136/0x1d0
   ksys_read+0x70/0xf0
   __x64_sys_read+0x1a/0x20
   do_syscall_64+0x3b/0xc0
   entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix this by checking that the aligned zone_movable_pfn[] does not exceed
the end of the node, and if it does skip creating a movable zone on this
node.

Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com
Fixes: 2a1e274 ("Create the ZONE_MOVABLE zone")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 23, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 23, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 23, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 23, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 23, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 24, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 25, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ammarfaizi2 pushed a commit to ammarfaizi2/linux-fork that referenced this pull request Apr 25, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging-kernelci-org pushed a commit to kernelci/linux that referenced this pull request Apr 26, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
intersectRaven pushed a commit to intersectRaven/linux that referenced this pull request Apr 26, 2023
commit 1ba1199 upstream.

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dcambie pushed a commit to dcambie/linux that referenced this pull request Apr 27, 2023
KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards. 
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs(). 
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1054009064 pushed a commit to 1054009064/linux that referenced this pull request May 11, 2023
[ Upstream commit 1ba1199 ]

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
1054009064 pushed a commit to 1054009064/linux that referenced this pull request May 17, 2023
[ Upstream commit 1ba1199 ]

KASAN report null-ptr-deref:
==================================================================
BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0
Write of size 8 at addr 0000000000000000 by task sync/943
CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty torvalds#461
Call Trace:
 <TASK>
 dump_stack_lvl+0x7f/0xc0
 print_report+0x2ba/0x340
 kasan_report+0xc4/0x120
 kasan_check_range+0x1b7/0x2e0
 __kasan_check_write+0x24/0x40
 bdi_split_work_to_wbs+0x5c5/0x7b0
 sync_inodes_sb+0x195/0x630
 sync_inodes_one_sb+0x3a/0x50
 iterate_supers+0x106/0x1b0
 ksys_sync+0x98/0x160
[...]
==================================================================

The race that causes the above issue is as follows:

           cpu1                     cpu2
-------------------------|-------------------------
inode_switch_wbs
 INIT_WORK(&isw->work, inode_switch_wbs_work_fn)
 queue_rcu_work(isw_wq, &isw->work)
 // queue_work async
  inode_switch_wbs_work_fn
   wb_put_many(old_wb, nr_switched)
    percpu_ref_put_many
     ref->data->release(ref)
     cgwb_release
      queue_work(cgwb_release_wq, &wb->release_work)
      // queue_work async
       &wb->release_work
       cgwb_release_workfn
                            ksys_sync
                             iterate_supers
                              sync_inodes_one_sb
                               sync_inodes_sb
                                bdi_split_work_to_wbs
                                 kmalloc(sizeof(*work), GFP_ATOMIC)
                                 // alloc memory failed
        percpu_ref_exit
         ref->data = NULL
         kfree(data)
                                 wb_get(wb)
                                  percpu_ref_get(&wb->refcnt)
                                   percpu_ref_get_many(ref, 1)
                                    atomic_long_add(nr, &ref->data->count)
                                     atomic64_add(i, v)
                                     // trigger null-ptr-deref

bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all
wbs.  If the allocation of new work fails, the on-stack fallback will be
used and the reference count of the current wb is increased afterwards.
If cgroup writeback membership switches occur before getting the reference
count and the current wb is released as old_wd, then calling wb_get() or
wb_put() will trigger the null pointer dereference above.

This issue was introduced in v4.3-rc7 (see fix tag1).  Both
sync_inodes_sb() and __writeback_inodes_sb_nr() calls to
bdi_split_work_to_wbs() can trigger this issue.  For scenarios called via
sync_inodes_sb(), originally commit 7fc5854 ("writeback: synchronize
sync(2) against cgroup writeback membership switches") reduced the
possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see
fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from
inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io,
thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(),
and the issue becomes easily reproducible again.

To solve this problem, percpu_ref_exit() is called under RCU protection to
avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs().
Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(),
and skip the current wb if wb_tryget() fails because the wb has already
been shutdown.

Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com
Fixes: b817525 ("writeback: bdi_writeback iteration must not skip dying ones")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hou Tao <houtao1@huawei.com>
Cc: yangerkun <yangerkun@huawei.com>
Cc: Zhang Yi <yi.zhang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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