Enabling WDS #461

ramonfontes · 2017-09-17T11:37:46Z

Sample video demonstration: https://www.youtube.com/watch?v=a27qWHO8JDM

KernelPRBot · 2017-09-17T11:40:07Z

Thanks for your contribution to the Linux kernel!

Linux kernel development happens on mailing lists, rather than on GitHub - this GitHub repository is a read-only mirror that isn't used for accepting contributions. So that your change can become part of Linux, please email it to us as a patch.

Sending patches isn't quite as simple as sending a pull request, but fortunately it is a well documented process.

Here's what to do:

Format your contribution according to kernel requirements
Decide who to send your contribution to
Set up your system to send your contribution as an email
Send your contribution and wait for feedback

How do I format my contribution?

The Linux kernel community is notoriously picky about how contributions are formatted and sent. Fortunately, they have documented their expectations.

Firstly, all contributions need to be formatted as patches. A patch is a plain text document showing the change you want to make to the code, and documenting why it is a good idea.

You can create patches with git format-patch.

Secondly, patches need 'commit messages', which is the human-friendly documentation explaining what the change is and why it's necessary.

Thirdly, changes have some technical requirements. There is a Linux kernel coding style, and there are licensing requirements you need to comply with.

Both of these are documented in the Submitting Patches documentation that is part of the kernel.

Note that you will almost certainly have to modify your existing git commits to satisfy these requirements. Don't worry: there are many guides on the internet for doing this.

Who do I send my contribution to?

The Linux kernel is composed of a number of subsystems. These subsystems are maintained by different people, and have different mailing lists where they discuss proposed changes.

If you don't already know what subsystem your change belongs to, the get_maintainer.pl script in the kernel source can help you.

get_maintainer.pl will take the patch or patches you created in the previous step, and tell you who is responsible for them, and what mailing lists are used. You can also take a look at the MAINTAINERS file by hand.

Make sure that your list of recipients includes a mailing list. If you can't find a more specific mailing list, then LKML - the Linux Kernel Mailing List - is the place to send your patches.

It's not usually necessary to subscribe to the mailing list before you send the patches, but if you're interested in kernel development, subscribing to a subsystem mailing list is a good idea. (At this point, you probably don't need to subscribe to LKML - it is a very high traffic list with about a thousand messages per day, which is often not useful for beginners.)

How do I send my contribution?

Use git send-email, which will ensure that your patches are formatted in the standard manner. In order to use git send-email, you'll need to configure git to use your SMTP email server.

For more information about using git send-email, look at the Git documentation or type git help send-email. There are a number of useful guides and tutorials about git send-email that can be found on the internet.

How do I get help if I'm stuck?

Firstly, don't get discouraged! There are an enormous number of resources on the internet, and many kernel developers who would like to see you succeed.

Many issues - especially about how to use certain tools - can be resolved by using your favourite internet search engine.

If you can't find an answer, there are a few places you can turn:

Kernel Newbies - this website contains a lot of useful resources for new kernel developers.
If you'd like a step-by-step, challenge-based introduction to kernel development, the Eudyptula Challenge would be an excellent start.
The kernel documentation - see also the Documentation directory in the kernel tree.

If you get really, really stuck, you could try the owners of this bot, @daxtens and @ajdlinux. Please be aware that we do have full-time jobs, so we are almost certainly the slowest way to get answers!

I sent my patch - now what?

You wait.

You can check that your email has been received by checking the mailing list archives for the mailing list you sent your patch to. Messages may not be received instantly, so be patient. Kernel developers are generally very busy people, so it may take a few weeks before your patch is looked at.

Then, you keep waiting. Three things may happen:

You might get a response to your email. Often these will be comments, which may require you to make changes to your patch, or explain why your way is the best way. You should respond to these comments, and you may need to submit another revision of your patch to address the issues raised.
Your patch might be merged into the subsystem tree. Code that becomes part of Linux isn't merged into the main repository straight away - it first goes into the subsystem tree, which is managed by the subsystem maintainer. It is then batched up with a number of other changes sent to Linus for inclusion. (This process is described in some detail in the kernel development process guide).
Your patch might be ignored completely. This happens sometimes - don't take it personally. Here's what to do:
- Wait a bit more - patches often take several weeks to get a response; more if they were sent at a busy time.
- Kernel developers often silently ignore patches that break the rules. Check for obvious violations of the the Submitting Patches guidelines, the style guidelines, and any other documentation you can find about your subsystem. Check that you're sending your patch to the right place.
- Try again later. When you resend it, don't add angry commentary, as that will get your patch ignored. It might also get you silently blacklisted.

Further information

Working with the kernel development community - the official documentation for new kernel contributors

Happy hacking!

This message was posted by a bot - if you have any questions or suggestions, please talk to my owners, @ajdlinux and @daxtens, or raise an issue at https://github.com/ajdlinux/KernelPRBot.

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>

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>

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>

[ 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>

rust: add a power management module.

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")

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>

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>

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>

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>

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>

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>

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>

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>

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>

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>

[ 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>

Enabling WDS

0d9bef6

Sample video demonstration: https://www.youtube.com/watch?v=a27qWHO8JDM

ojeda added a commit to ojeda/linux that referenced this pull request Jul 29, 2021

Merge pull request torvalds#461 from wedsonaf/power

7aa46b0

rust: add a power management module.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Enabling WDS #461

Enabling WDS #461

ramonfontes commented Sep 17, 2017

KernelPRBot commented Sep 17, 2017

Enabling WDS #461

Are you sure you want to change the base?

Enabling WDS #461

Conversation

ramonfontes commented Sep 17, 2017

KernelPRBot commented Sep 17, 2017

How do I format my contribution?

Who do I send my contribution to?

How do I send my contribution?

How do I get help if I'm stuck?

I sent my patch - now what?

Further information