Merge pull request #1 from torvalds/master #275

nanszy · 2016-04-13T11:12:22Z

update

lkl: add dhcp client option

If a hashtab is accessed in both NMI and non-NMI contexts, it may cause deadlock in bucket->lock. LOCKDEP NMI warning highlighted this issue: ./test_progs -t stacktrace [ 74.828970] [ 74.828971] ================================ [ 74.828972] WARNING: inconsistent lock state [ 74.828973] 5.9.0-rc8+ torvalds#275 Not tainted [ 74.828974] -------------------------------- [ 74.828975] inconsistent {INITIAL USE} -> {IN-NMI} usage. [ 74.828976] taskset/1174 [HC2[2]:SC0[0]:HE0:SE1] takes: [ 74.828977] ffffc90000ee96b0 (&htab->buckets[i].raw_lock){....}-{2:2}, at: htab_map_update_elem+0x271/0x5a0 [ 74.828981] {INITIAL USE} state was registered at: [ 74.828982] lock_acquire+0x137/0x510 [ 74.828983] _raw_spin_lock_irqsave+0x43/0x90 [ 74.828984] htab_map_update_elem+0x271/0x5a0 [ 74.828984] 0xffffffffa0040b34 [ 74.828985] trace_call_bpf+0x159/0x310 [ 74.828986] perf_trace_run_bpf_submit+0x5f/0xd0 [ 74.828987] perf_trace_urandom_read+0x1be/0x220 [ 74.828988] urandom_read_nowarn.isra.0+0x26f/0x380 [ 74.828989] vfs_read+0xf8/0x280 [ 74.828989] ksys_read+0xc9/0x160 [ 74.828990] do_syscall_64+0x33/0x40 [ 74.828991] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 74.828992] irq event stamp: 1766 [ 74.828993] hardirqs last enabled at (1765): [<ffffffff82800ace>] asm_exc_page_fault+0x1e/0x30 [ 74.828994] hardirqs last disabled at (1766): [<ffffffff8267df87>] irqentry_enter+0x37/0x60 [ 74.828995] softirqs last enabled at (856): [<ffffffff81043e7c>] fpu__clear+0xac/0x120 [ 74.828996] softirqs last disabled at (854): [<ffffffff81043df0>] fpu__clear+0x20/0x120 [ 74.828997] [ 74.828998] other info that might help us debug this: [ 74.828999] Possible unsafe locking scenario: [ 74.828999] [ 74.829000] CPU0 [ 74.829001] ---- [ 74.829001] lock(&htab->buckets[i].raw_lock); [ 74.829003] <Interrupt> [ 74.829004] lock(&htab->buckets[i].raw_lock); [ 74.829006] [ 74.829006] *** DEADLOCK *** [ 74.829007] [ 74.829008] 1 lock held by taskset/1174: [ 74.829008] #0: ffff8883ec3fd020 (&cpuctx_lock){-...}-{2:2}, at: perf_event_task_tick+0x101/0x650 [ 74.829012] [ 74.829013] stack backtrace: [ 74.829014] CPU: 0 PID: 1174 Comm: taskset Not tainted 5.9.0-rc8+ torvalds#275 [ 74.829015] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 [ 74.829016] Call Trace: [ 74.829016] <NMI> [ 74.829017] dump_stack+0x9a/0xd0 [ 74.829018] lock_acquire+0x461/0x510 [ 74.829019] ? lock_release+0x6b0/0x6b0 [ 74.829020] ? stack_map_get_build_id_offset+0x45e/0x800 [ 74.829021] ? htab_map_update_elem+0x271/0x5a0 [ 74.829022] ? rcu_read_lock_held_common+0x1a/0x50 [ 74.829022] ? rcu_read_lock_held+0x5f/0xb0 [ 74.829023] _raw_spin_lock_irqsave+0x43/0x90 [ 74.829024] ? htab_map_update_elem+0x271/0x5a0 [ 74.829025] htab_map_update_elem+0x271/0x5a0 [ 74.829026] bpf_prog_1fd9e30e1438d3c5_oncpu+0x9c/0xe88 [ 74.829027] bpf_overflow_handler+0x127/0x320 [ 74.829028] ? perf_event_text_poke_output+0x4d0/0x4d0 [ 74.829029] ? sched_clock_cpu+0x18/0x130 [ 74.829030] __perf_event_overflow+0xae/0x190 [ 74.829030] handle_pmi_common+0x34c/0x470 [ 74.829031] ? intel_pmu_save_and_restart+0x90/0x90 [ 74.829032] ? lock_acquire+0x3f8/0x510 [ 74.829033] ? lock_release+0x6b0/0x6b0 [ 74.829034] intel_pmu_handle_irq+0x11e/0x240 [ 74.829034] perf_event_nmi_handler+0x40/0x60 [ 74.829035] nmi_handle+0x110/0x360 [ 74.829036] ? __intel_pmu_enable_all.constprop.0+0x72/0xf0 [ 74.829037] default_do_nmi+0x6b/0x170 [ 74.829038] exc_nmi+0x106/0x130 [ 74.829038] end_repeat_nmi+0x16/0x55 [ 74.829039] RIP: 0010:__intel_pmu_enable_all.constprop.0+0x72/0xf0 [ 74.829042] Code: 2f 1f 03 48 8d bb b8 0c 00 00 e8 29 09 41 00 48 ... [ 74.829043] RSP: 0000:ffff8880a604fc90 EFLAGS: 00000002 [ 74.829044] RAX: 000000070000000f RBX: ffff8883ec2195a0 RCX: 000000000000038f [ 74.829045] RDX: 0000000000000007 RSI: ffffffff82e72c20 RDI: ffff8883ec21a258 [ 74.829046] RBP: 000000070000000f R08: ffffffff8101b013 R09: fffffbfff0a7982d [ 74.829047] R10: ffffffff853cc167 R11: fffffbfff0a7982c R12: 0000000000000000 [ 74.829049] R13: ffff8883ec3f0af0 R14: ffff8883ec3fd120 R15: ffff8883e9c92098 [ 74.829049] ? intel_pmu_lbr_enable_all+0x43/0x240 [ 74.829050] ? __intel_pmu_enable_all.constprop.0+0x72/0xf0 [ 74.829051] ? __intel_pmu_enable_all.constprop.0+0x72/0xf0 [ 74.829052] </NMI> [ 74.829053] perf_event_task_tick+0x48d/0x650 [ 74.829054] scheduler_tick+0x129/0x210 [ 74.829054] update_process_times+0x37/0x70 [ 74.829055] tick_sched_handle.isra.0+0x35/0x90 [ 74.829056] tick_sched_timer+0x8f/0xb0 [ 74.829057] __hrtimer_run_queues+0x364/0x7d0 [ 74.829058] ? tick_sched_do_timer+0xa0/0xa0 [ 74.829058] ? enqueue_hrtimer+0x1e0/0x1e0 [ 74.829059] ? recalibrate_cpu_khz+0x10/0x10 [ 74.829060] ? ktime_get_update_offsets_now+0x1a3/0x360 [ 74.829061] hrtimer_interrupt+0x1bb/0x360 [ 74.829062] ? rcu_read_lock_sched_held+0xa1/0xd0 [ 74.829063] __sysvec_apic_timer_interrupt+0xed/0x3d0 [ 74.829064] sysvec_apic_timer_interrupt+0x3f/0xd0 [ 74.829064] ? asm_sysvec_apic_timer_interrupt+0xa/0x20 [ 74.829065] asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 74.829066] RIP: 0033:0x7fba18d579b4 [ 74.829068] Code: 74 54 44 0f b6 4a 04 41 83 e1 0f 41 80 f9 ... [ 74.829069] RSP: 002b:00007ffc9ba69570 EFLAGS: 00000206 [ 74.829071] RAX: 00007fba192084c0 RBX: 00007fba18c24d28 RCX: 00000000000007a4 [ 74.829072] RDX: 00007fba18c30488 RSI: 0000000000000000 RDI: 000000000000037b [ 74.829073] RBP: 00007fba18ca5760 R08: 00007fba18c248fc R09: 00007fba18c94c30 [ 74.829074] R10: 000000000000002f R11: 0000000000073c30 R12: 00007ffc9ba695e0 [ 74.829075] R13: 00000000000003f3 R14: 00007fba18c21ac8 R15: 00000000000058d6 However, such warning should not apply across multiple hashtabs. The system will not deadlock if one hashtab is used in NMI, while another hashtab is used in non-NMI. Use separate lockdep class for each hashtab, so that we don't get this false alert. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201029071925.3103400-2-songliubraving@fb.com

Song Liu says: ==================== LOCKDEP NMI warning highlighted potential deadlock of hashtab in NMI context: [ 74.828971] ================================ [ 74.828972] WARNING: inconsistent lock state [ 74.828973] 5.9.0-rc8+ torvalds#275 Not tainted [ 74.828974] -------------------------------- [ 74.828975] inconsistent {INITIAL USE} -> {IN-NMI} usage. [ 74.828976] taskset/1174 [HC2[2]:SC0[0]:HE0:SE1] takes: [...] [ 74.828999] Possible unsafe locking scenario: [ 74.828999] [ 74.829000] CPU0 [ 74.829001] ---- [ 74.829001] lock(&htab->buckets[i].raw_lock); [ 74.829003] <Interrupt> [ 74.829004] lock(&htab->buckets[i].raw_lock); Please refer to patch 1/2 for full trace. This warning is a false alert, as "INITIAL USE" and "IN-NMI" in the tests are from different hashtab. On the other hand, in theory, it is possible to deadlock when a hashtab is access from both non-NMI and NMI context. Patch 1/2 fixes this false alert by assigning separate lockdep class to each hashtab. Patch 2/2 introduces map_locked counters, which is similar to bpf_prog_active counter, to avoid hashtab deadlock in NMI context. ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org>

…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. torvalds#269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK torvalds#270/p pass ctx or null check, 2: null Did not run the program (not supported) OK torvalds#271/p pass ctx or null check, 3: 1 OK torvalds#272/p pass ctx or null check, 4: ctx - const OK torvalds#273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK torvalds#274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK torvalds#275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK torvalds#276/p pass ctx or null check, 8: null (bind) OK torvalds#277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK torvalds#278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>

WARNING: please, no spaces at the start of a line torvalds#249: FILE: mm/page-writeback.c:2089: + {$ ERROR: code indent should use tabs where possible torvalds#250: FILE: mm/page-writeback.c:2090: + .procname = "dirty_background_ratio",$ WARNING: please, no spaces at the start of a line torvalds#250: FILE: mm/page-writeback.c:2090: + .procname = "dirty_background_ratio",$ ERROR: code indent should use tabs where possible torvalds#251: FILE: mm/page-writeback.c:2091: + .data = &dirty_background_ratio,$ WARNING: please, no spaces at the start of a line torvalds#251: FILE: mm/page-writeback.c:2091: + .data = &dirty_background_ratio,$ ERROR: code indent should use tabs where possible torvalds#252: FILE: mm/page-writeback.c:2092: + .maxlen = sizeof(dirty_background_ratio),$ WARNING: please, no spaces at the start of a line torvalds#252: FILE: mm/page-writeback.c:2092: + .maxlen = sizeof(dirty_background_ratio),$ ERROR: code indent should use tabs where possible torvalds#253: FILE: mm/page-writeback.c:2093: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#253: FILE: mm/page-writeback.c:2093: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#254: FILE: mm/page-writeback.c:2094: + .proc_handler = dirty_background_ratio_handler,$ WARNING: please, no spaces at the start of a line torvalds#254: FILE: mm/page-writeback.c:2094: + .proc_handler = dirty_background_ratio_handler,$ ERROR: code indent should use tabs where possible torvalds#255: FILE: mm/page-writeback.c:2095: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#255: FILE: mm/page-writeback.c:2095: + .extra1 = SYSCTL_ZERO,$ ERROR: code indent should use tabs where possible torvalds#256: FILE: mm/page-writeback.c:2096: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#256: FILE: mm/page-writeback.c:2096: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#257: FILE: mm/page-writeback.c:2097: + },$ WARNING: please, no spaces at the start of a line torvalds#258: FILE: mm/page-writeback.c:2098: + {$ ERROR: code indent should use tabs where possible torvalds#259: FILE: mm/page-writeback.c:2099: + .procname = "dirty_background_bytes",$ WARNING: please, no spaces at the start of a line torvalds#259: FILE: mm/page-writeback.c:2099: + .procname = "dirty_background_bytes",$ ERROR: code indent should use tabs where possible torvalds#260: FILE: mm/page-writeback.c:2100: + .data = &dirty_background_bytes,$ WARNING: please, no spaces at the start of a line torvalds#260: FILE: mm/page-writeback.c:2100: + .data = &dirty_background_bytes,$ ERROR: code indent should use tabs where possible torvalds#261: FILE: mm/page-writeback.c:2101: + .maxlen = sizeof(dirty_background_bytes),$ WARNING: please, no spaces at the start of a line torvalds#261: FILE: mm/page-writeback.c:2101: + .maxlen = sizeof(dirty_background_bytes),$ ERROR: code indent should use tabs where possible torvalds#262: FILE: mm/page-writeback.c:2102: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#262: FILE: mm/page-writeback.c:2102: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#263: FILE: mm/page-writeback.c:2103: + .proc_handler = dirty_background_bytes_handler,$ WARNING: please, no spaces at the start of a line torvalds#263: FILE: mm/page-writeback.c:2103: + .proc_handler = dirty_background_bytes_handler,$ ERROR: code indent should use tabs where possible torvalds#264: FILE: mm/page-writeback.c:2104: + .extra1 = SYSCTL_LONG_ONE,$ WARNING: please, no spaces at the start of a line torvalds#264: FILE: mm/page-writeback.c:2104: + .extra1 = SYSCTL_LONG_ONE,$ WARNING: please, no spaces at the start of a line torvalds#265: FILE: mm/page-writeback.c:2105: + },$ WARNING: please, no spaces at the start of a line torvalds#266: FILE: mm/page-writeback.c:2106: + {$ ERROR: code indent should use tabs where possible torvalds#267: FILE: mm/page-writeback.c:2107: + .procname = "dirty_ratio",$ WARNING: please, no spaces at the start of a line torvalds#267: FILE: mm/page-writeback.c:2107: + .procname = "dirty_ratio",$ ERROR: code indent should use tabs where possible torvalds#268: FILE: mm/page-writeback.c:2108: + .data = &vm_dirty_ratio,$ WARNING: please, no spaces at the start of a line torvalds#268: FILE: mm/page-writeback.c:2108: + .data = &vm_dirty_ratio,$ ERROR: code indent should use tabs where possible torvalds#269: FILE: mm/page-writeback.c:2109: + .maxlen = sizeof(vm_dirty_ratio),$ WARNING: please, no spaces at the start of a line torvalds#269: FILE: mm/page-writeback.c:2109: + .maxlen = sizeof(vm_dirty_ratio),$ ERROR: code indent should use tabs where possible torvalds#270: FILE: mm/page-writeback.c:2110: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#270: FILE: mm/page-writeback.c:2110: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#271: FILE: mm/page-writeback.c:2111: + .proc_handler = dirty_ratio_handler,$ WARNING: please, no spaces at the start of a line torvalds#271: FILE: mm/page-writeback.c:2111: + .proc_handler = dirty_ratio_handler,$ ERROR: code indent should use tabs where possible torvalds#272: FILE: mm/page-writeback.c:2112: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#272: FILE: mm/page-writeback.c:2112: + .extra1 = SYSCTL_ZERO,$ ERROR: code indent should use tabs where possible torvalds#273: FILE: mm/page-writeback.c:2113: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#273: FILE: mm/page-writeback.c:2113: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#274: FILE: mm/page-writeback.c:2114: + },$ WARNING: please, no spaces at the start of a line torvalds#275: FILE: mm/page-writeback.c:2115: + {$ ERROR: code indent should use tabs where possible torvalds#276: FILE: mm/page-writeback.c:2116: + .procname = "dirty_bytes",$ WARNING: please, no spaces at the start of a line torvalds#276: FILE: mm/page-writeback.c:2116: + .procname = "dirty_bytes",$ ERROR: code indent should use tabs where possible torvalds#277: FILE: mm/page-writeback.c:2117: + .data = &vm_dirty_bytes,$ WARNING: please, no spaces at the start of a line torvalds#277: FILE: mm/page-writeback.c:2117: + .data = &vm_dirty_bytes,$ ERROR: code indent should use tabs where possible torvalds#278: FILE: mm/page-writeback.c:2118: + .maxlen = sizeof(vm_dirty_bytes),$ WARNING: please, no spaces at the start of a line torvalds#278: FILE: mm/page-writeback.c:2118: + .maxlen = sizeof(vm_dirty_bytes),$ ERROR: code indent should use tabs where possible torvalds#279: FILE: mm/page-writeback.c:2119: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#279: FILE: mm/page-writeback.c:2119: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#280: FILE: mm/page-writeback.c:2120: + .proc_handler = dirty_bytes_handler,$ WARNING: please, no spaces at the start of a line torvalds#280: FILE: mm/page-writeback.c:2120: + .proc_handler = dirty_bytes_handler,$ ERROR: code indent should use tabs where possible torvalds#281: FILE: mm/page-writeback.c:2121: + .extra1 = (void *)&dirty_bytes_min,$ WARNING: please, no spaces at the start of a line torvalds#281: FILE: mm/page-writeback.c:2121: + .extra1 = (void *)&dirty_bytes_min,$ WARNING: please, no spaces at the start of a line torvalds#282: FILE: mm/page-writeback.c:2122: + },$ WARNING: please, no spaces at the start of a line torvalds#283: FILE: mm/page-writeback.c:2123: + {$ ERROR: code indent should use tabs where possible torvalds#284: FILE: mm/page-writeback.c:2124: + .procname = "dirty_writeback_centisecs",$ WARNING: please, no spaces at the start of a line torvalds#284: FILE: mm/page-writeback.c:2124: + .procname = "dirty_writeback_centisecs",$ ERROR: code indent should use tabs where possible torvalds#285: FILE: mm/page-writeback.c:2125: + .data = &dirty_writeback_interval,$ WARNING: please, no spaces at the start of a line torvalds#285: FILE: mm/page-writeback.c:2125: + .data = &dirty_writeback_interval,$ ERROR: code indent should use tabs where possible torvalds#286: FILE: mm/page-writeback.c:2126: + .maxlen = sizeof(dirty_writeback_interval),$ WARNING: please, no spaces at the start of a line torvalds#286: FILE: mm/page-writeback.c:2126: + .maxlen = sizeof(dirty_writeback_interval),$ ERROR: code indent should use tabs where possible torvalds#287: FILE: mm/page-writeback.c:2127: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#287: FILE: mm/page-writeback.c:2127: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#288: FILE: mm/page-writeback.c:2128: + .proc_handler = dirty_writeback_centisecs_handler,$ WARNING: please, no spaces at the start of a line torvalds#288: FILE: mm/page-writeback.c:2128: + .proc_handler = dirty_writeback_centisecs_handler,$ WARNING: please, no spaces at the start of a line torvalds#289: FILE: mm/page-writeback.c:2129: + },$ WARNING: please, no spaces at the start of a line torvalds#290: FILE: mm/page-writeback.c:2130: + {$ ERROR: code indent should use tabs where possible torvalds#291: FILE: mm/page-writeback.c:2131: + .procname = "dirty_expire_centisecs",$ WARNING: please, no spaces at the start of a line torvalds#291: FILE: mm/page-writeback.c:2131: + .procname = "dirty_expire_centisecs",$ ERROR: code indent should use tabs where possible torvalds#292: FILE: mm/page-writeback.c:2132: + .data = &dirty_expire_interval,$ WARNING: please, no spaces at the start of a line torvalds#292: FILE: mm/page-writeback.c:2132: + .data = &dirty_expire_interval,$ ERROR: code indent should use tabs where possible torvalds#293: FILE: mm/page-writeback.c:2133: + .maxlen = sizeof(dirty_expire_interval),$ WARNING: please, no spaces at the start of a line torvalds#293: FILE: mm/page-writeback.c:2133: + .maxlen = sizeof(dirty_expire_interval),$ ERROR: code indent should use tabs where possible torvalds#294: FILE: mm/page-writeback.c:2134: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#294: FILE: mm/page-writeback.c:2134: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#295: FILE: mm/page-writeback.c:2135: + .proc_handler = proc_dointvec_minmax,$ WARNING: please, no spaces at the start of a line torvalds#295: FILE: mm/page-writeback.c:2135: + .proc_handler = proc_dointvec_minmax,$ ERROR: code indent should use tabs where possible torvalds#296: FILE: mm/page-writeback.c:2136: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#296: FILE: mm/page-writeback.c:2136: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#297: FILE: mm/page-writeback.c:2137: + },$ total: 37 errors, 49 warnings, 287 lines checked NOTE: For some of the reported defects, checkpatch may be able to mechanically convert to the typical style using --fix or --fix-inplace. NOTE: Whitespace errors detected. You may wish to use scripts/cleanpatch or scripts/cleanfile ./patches/mm-move-page-writeback-sysctls-to-is-own-file.patch has style problems, please review. NOTE: If any of the errors are false positives, please report them to the maintainer, see CHECKPATCH in MAINTAINERS. Please run checkpatch prior to sending patches Cc: Iurii Zaikin <yzaikin@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: zhanglianjie <zhanglianjie@uniontech.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

WARNING: please, no spaces at the start of a line torvalds#249: FILE: mm/page-writeback.c:2089: + {$ ERROR: code indent should use tabs where possible torvalds#250: FILE: mm/page-writeback.c:2090: + .procname = "dirty_background_ratio",$ WARNING: please, no spaces at the start of a line torvalds#250: FILE: mm/page-writeback.c:2090: + .procname = "dirty_background_ratio",$ ERROR: code indent should use tabs where possible torvalds#251: FILE: mm/page-writeback.c:2091: + .data = &dirty_background_ratio,$ WARNING: please, no spaces at the start of a line torvalds#251: FILE: mm/page-writeback.c:2091: + .data = &dirty_background_ratio,$ ERROR: code indent should use tabs where possible torvalds#252: FILE: mm/page-writeback.c:2092: + .maxlen = sizeof(dirty_background_ratio),$ WARNING: please, no spaces at the start of a line torvalds#252: FILE: mm/page-writeback.c:2092: + .maxlen = sizeof(dirty_background_ratio),$ ERROR: code indent should use tabs where possible torvalds#253: FILE: mm/page-writeback.c:2093: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#253: FILE: mm/page-writeback.c:2093: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#254: FILE: mm/page-writeback.c:2094: + .proc_handler = dirty_background_ratio_handler,$ WARNING: please, no spaces at the start of a line torvalds#254: FILE: mm/page-writeback.c:2094: + .proc_handler = dirty_background_ratio_handler,$ ERROR: code indent should use tabs where possible torvalds#255: FILE: mm/page-writeback.c:2095: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#255: FILE: mm/page-writeback.c:2095: + .extra1 = SYSCTL_ZERO,$ ERROR: code indent should use tabs where possible torvalds#256: FILE: mm/page-writeback.c:2096: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#256: FILE: mm/page-writeback.c:2096: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#257: FILE: mm/page-writeback.c:2097: + },$ WARNING: please, no spaces at the start of a line torvalds#258: FILE: mm/page-writeback.c:2098: + {$ ERROR: code indent should use tabs where possible torvalds#259: FILE: mm/page-writeback.c:2099: + .procname = "dirty_background_bytes",$ WARNING: please, no spaces at the start of a line torvalds#259: FILE: mm/page-writeback.c:2099: + .procname = "dirty_background_bytes",$ ERROR: code indent should use tabs where possible torvalds#260: FILE: mm/page-writeback.c:2100: + .data = &dirty_background_bytes,$ WARNING: please, no spaces at the start of a line torvalds#260: FILE: mm/page-writeback.c:2100: + .data = &dirty_background_bytes,$ ERROR: code indent should use tabs where possible torvalds#261: FILE: mm/page-writeback.c:2101: + .maxlen = sizeof(dirty_background_bytes),$ WARNING: please, no spaces at the start of a line torvalds#261: FILE: mm/page-writeback.c:2101: + .maxlen = sizeof(dirty_background_bytes),$ ERROR: code indent should use tabs where possible torvalds#262: FILE: mm/page-writeback.c:2102: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#262: FILE: mm/page-writeback.c:2102: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#263: FILE: mm/page-writeback.c:2103: + .proc_handler = dirty_background_bytes_handler,$ WARNING: please, no spaces at the start of a line torvalds#263: FILE: mm/page-writeback.c:2103: + .proc_handler = dirty_background_bytes_handler,$ ERROR: code indent should use tabs where possible torvalds#264: FILE: mm/page-writeback.c:2104: + .extra1 = SYSCTL_LONG_ONE,$ WARNING: please, no spaces at the start of a line torvalds#264: FILE: mm/page-writeback.c:2104: + .extra1 = SYSCTL_LONG_ONE,$ WARNING: please, no spaces at the start of a line torvalds#265: FILE: mm/page-writeback.c:2105: + },$ WARNING: please, no spaces at the start of a line torvalds#266: FILE: mm/page-writeback.c:2106: + {$ ERROR: code indent should use tabs where possible torvalds#267: FILE: mm/page-writeback.c:2107: + .procname = "dirty_ratio",$ WARNING: please, no spaces at the start of a line torvalds#267: FILE: mm/page-writeback.c:2107: + .procname = "dirty_ratio",$ ERROR: code indent should use tabs where possible torvalds#268: FILE: mm/page-writeback.c:2108: + .data = &vm_dirty_ratio,$ WARNING: please, no spaces at the start of a line torvalds#268: FILE: mm/page-writeback.c:2108: + .data = &vm_dirty_ratio,$ ERROR: code indent should use tabs where possible torvalds#269: FILE: mm/page-writeback.c:2109: + .maxlen = sizeof(vm_dirty_ratio),$ WARNING: please, no spaces at the start of a line torvalds#269: FILE: mm/page-writeback.c:2109: + .maxlen = sizeof(vm_dirty_ratio),$ ERROR: code indent should use tabs where possible torvalds#270: FILE: mm/page-writeback.c:2110: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#270: FILE: mm/page-writeback.c:2110: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#271: FILE: mm/page-writeback.c:2111: + .proc_handler = dirty_ratio_handler,$ WARNING: please, no spaces at the start of a line torvalds#271: FILE: mm/page-writeback.c:2111: + .proc_handler = dirty_ratio_handler,$ ERROR: code indent should use tabs where possible torvalds#272: FILE: mm/page-writeback.c:2112: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#272: FILE: mm/page-writeback.c:2112: + .extra1 = SYSCTL_ZERO,$ ERROR: code indent should use tabs where possible torvalds#273: FILE: mm/page-writeback.c:2113: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#273: FILE: mm/page-writeback.c:2113: + .extra2 = SYSCTL_ONE_HUNDRED,$ WARNING: please, no spaces at the start of a line torvalds#274: FILE: mm/page-writeback.c:2114: + },$ WARNING: please, no spaces at the start of a line torvalds#275: FILE: mm/page-writeback.c:2115: + {$ ERROR: code indent should use tabs where possible torvalds#276: FILE: mm/page-writeback.c:2116: + .procname = "dirty_bytes",$ WARNING: please, no spaces at the start of a line torvalds#276: FILE: mm/page-writeback.c:2116: + .procname = "dirty_bytes",$ ERROR: code indent should use tabs where possible torvalds#277: FILE: mm/page-writeback.c:2117: + .data = &vm_dirty_bytes,$ WARNING: please, no spaces at the start of a line torvalds#277: FILE: mm/page-writeback.c:2117: + .data = &vm_dirty_bytes,$ ERROR: code indent should use tabs where possible torvalds#278: FILE: mm/page-writeback.c:2118: + .maxlen = sizeof(vm_dirty_bytes),$ WARNING: please, no spaces at the start of a line torvalds#278: FILE: mm/page-writeback.c:2118: + .maxlen = sizeof(vm_dirty_bytes),$ ERROR: code indent should use tabs where possible torvalds#279: FILE: mm/page-writeback.c:2119: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#279: FILE: mm/page-writeback.c:2119: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#280: FILE: mm/page-writeback.c:2120: + .proc_handler = dirty_bytes_handler,$ WARNING: please, no spaces at the start of a line torvalds#280: FILE: mm/page-writeback.c:2120: + .proc_handler = dirty_bytes_handler,$ ERROR: code indent should use tabs where possible torvalds#281: FILE: mm/page-writeback.c:2121: + .extra1 = (void *)&dirty_bytes_min,$ WARNING: please, no spaces at the start of a line torvalds#281: FILE: mm/page-writeback.c:2121: + .extra1 = (void *)&dirty_bytes_min,$ WARNING: please, no spaces at the start of a line torvalds#282: FILE: mm/page-writeback.c:2122: + },$ WARNING: please, no spaces at the start of a line torvalds#283: FILE: mm/page-writeback.c:2123: + {$ ERROR: code indent should use tabs where possible torvalds#284: FILE: mm/page-writeback.c:2124: + .procname = "dirty_writeback_centisecs",$ WARNING: please, no spaces at the start of a line torvalds#284: FILE: mm/page-writeback.c:2124: + .procname = "dirty_writeback_centisecs",$ ERROR: code indent should use tabs where possible torvalds#285: FILE: mm/page-writeback.c:2125: + .data = &dirty_writeback_interval,$ WARNING: please, no spaces at the start of a line torvalds#285: FILE: mm/page-writeback.c:2125: + .data = &dirty_writeback_interval,$ ERROR: code indent should use tabs where possible torvalds#286: FILE: mm/page-writeback.c:2126: + .maxlen = sizeof(dirty_writeback_interval),$ WARNING: please, no spaces at the start of a line torvalds#286: FILE: mm/page-writeback.c:2126: + .maxlen = sizeof(dirty_writeback_interval),$ ERROR: code indent should use tabs where possible torvalds#287: FILE: mm/page-writeback.c:2127: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#287: FILE: mm/page-writeback.c:2127: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#288: FILE: mm/page-writeback.c:2128: + .proc_handler = dirty_writeback_centisecs_handler,$ WARNING: please, no spaces at the start of a line torvalds#288: FILE: mm/page-writeback.c:2128: + .proc_handler = dirty_writeback_centisecs_handler,$ WARNING: please, no spaces at the start of a line torvalds#289: FILE: mm/page-writeback.c:2129: + },$ WARNING: please, no spaces at the start of a line torvalds#290: FILE: mm/page-writeback.c:2130: + {$ ERROR: code indent should use tabs where possible torvalds#291: FILE: mm/page-writeback.c:2131: + .procname = "dirty_expire_centisecs",$ WARNING: please, no spaces at the start of a line torvalds#291: FILE: mm/page-writeback.c:2131: + .procname = "dirty_expire_centisecs",$ ERROR: code indent should use tabs where possible torvalds#292: FILE: mm/page-writeback.c:2132: + .data = &dirty_expire_interval,$ WARNING: please, no spaces at the start of a line torvalds#292: FILE: mm/page-writeback.c:2132: + .data = &dirty_expire_interval,$ ERROR: code indent should use tabs where possible torvalds#293: FILE: mm/page-writeback.c:2133: + .maxlen = sizeof(dirty_expire_interval),$ WARNING: please, no spaces at the start of a line torvalds#293: FILE: mm/page-writeback.c:2133: + .maxlen = sizeof(dirty_expire_interval),$ ERROR: code indent should use tabs where possible torvalds#294: FILE: mm/page-writeback.c:2134: + .mode = 0644,$ WARNING: please, no spaces at the start of a line torvalds#294: FILE: mm/page-writeback.c:2134: + .mode = 0644,$ ERROR: code indent should use tabs where possible torvalds#295: FILE: mm/page-writeback.c:2135: + .proc_handler = proc_dointvec_minmax,$ WARNING: please, no spaces at the start of a line torvalds#295: FILE: mm/page-writeback.c:2135: + .proc_handler = proc_dointvec_minmax,$ ERROR: code indent should use tabs where possible torvalds#296: FILE: mm/page-writeback.c:2136: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#296: FILE: mm/page-writeback.c:2136: + .extra1 = SYSCTL_ZERO,$ WARNING: please, no spaces at the start of a line torvalds#297: FILE: mm/page-writeback.c:2137: + },$ total: 37 errors, 49 warnings, 287 lines checked NOTE: For some of the reported defects, checkpatch may be able to mechanically convert to the typical style using --fix or --fix-inplace. NOTE: Whitespace errors detected. You may wish to use scripts/cleanpatch or scripts/cleanfile ./patches/mm-move-page-writeback-sysctls-to-is-own-file.patch has style problems, please review. NOTE: If any of the errors are false positives, please report them to the maintainer, see CHECKPATCH in MAINTAINERS. Please run checkpatch prior to sending patches Cc: Iurii Zaikin <yzaikin@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: zhanglianjie <zhanglianjie@uniontech.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Mark Brown <broonie@kernel.org>

Add test coverage for reservations beyond the ring buffer size in order to validate that bpf_ringbuf_reserve() rejects the request with NULL, all other ring buffer tests keep passing as well: # ./vmtest.sh -- ./test_progs -t ringbuf [...] ./test_progs -t ringbuf [ 1.165434] bpf_testmod: loading out-of-tree module taints kernel. [ 1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel [ 1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz [ 1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns [ 1.289555] clocksource: Switched to clocksource tsc torvalds#274/1 ringbuf/ringbuf:OK torvalds#274/2 ringbuf/ringbuf_n:OK torvalds#274/3 ringbuf/ringbuf_map_key:OK torvalds#274/4 ringbuf/ringbuf_write:OK torvalds#274 ringbuf:OK torvalds#275 ringbuf_multi:OK [...] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240621140828.18238-2-daniel@iogearbox.net

Add test coverage for reservations beyond the ring buffer size in order to validate that bpf_ringbuf_reserve() rejects the request with NULL, all other ring buffer tests keep passing as well: # ./vmtest.sh -- ./test_progs -t ringbuf [...] ./test_progs -t ringbuf [ 1.165434] bpf_testmod: loading out-of-tree module taints kernel. [ 1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel [ 1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz [ 1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns [ 1.289555] clocksource: Switched to clocksource tsc torvalds#274/1 ringbuf/ringbuf:OK torvalds#274/2 ringbuf/ringbuf_n:OK torvalds#274/3 ringbuf/ringbuf_map_key:OK torvalds#274/4 ringbuf/ringbuf_write:OK torvalds#274 ringbuf:OK torvalds#275 ringbuf_multi:OK [...] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> [ Test fixups for getting BPF CI back to work ] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240621140828.18238-2-daniel@iogearbox.net

Add test coverage for reservations beyond the ring buffer size in order to validate that bpf_ringbuf_reserve() rejects the request with NULL, all other ring buffer tests keep passing as well: # ./vmtest.sh -- ./test_progs -t ringbuf [...] ./test_progs -t ringbuf [ 1.165434] bpf_testmod: loading out-of-tree module taints kernel. [ 1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel [ 1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz [ 1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns [ 1.289555] clocksource: Switched to clocksource tsc torvalds#274/1 ringbuf/ringbuf:OK torvalds#274/2 ringbuf/ringbuf_n:OK torvalds#274/3 ringbuf/ringbuf_map_key:OK torvalds#274/4 ringbuf/ringbuf_write:OK torvalds#274 ringbuf:OK torvalds#275 ringbuf_multi:OK [...] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

@Dev-

uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add test coverage for reservations beyond the ring buffer size in order to validate that bpf_ringbuf_reserve() rejects the request with NULL, all other ring buffer tests keep passing as well: # ./vmtest.sh -- ./test_progs -t ringbuf [...] ./test_progs -t ringbuf [ 1.165434] bpf_testmod: loading out-of-tree module taints kernel. [ 1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel [ 1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz [ 1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns [ 1.289555] clocksource: Switched to clocksource tsc torvalds#274/1 ringbuf/ringbuf:OK torvalds#274/2 ringbuf/ringbuf_n:OK torvalds#274/3 ringbuf/ringbuf_map_key:OK torvalds#274/4 ringbuf/ringbuf_write:OK torvalds#274 ringbuf:OK torvalds#275 ringbuf_multi:OK [...] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> [ Test fixups for getting BPF CI back to work ] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240621140828.18238-2-daniel@iogearbox.net

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

commit 15fffc6 upstream. uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

@Dev-

uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock. This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @Dev->mutex to reveal reports of the form: ====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ torvalds#275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220 but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event. Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1]. Fixes: c0a4009 ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne.jp [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch Cc: stable@vger.kernel.org Cc: Ashish Sangwan <a.sangwan@samsung.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Dirk Behme <dirk.behme@de.bosch.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge pull request #1 from torvalds/master

550e249

update

nanszy closed this Apr 13, 2016

laijs pushed a commit to laijs/linux that referenced this pull request Feb 13, 2017

Merge pull request torvalds#275 from libos-nuse/feature-dhclient

e5d3c5c

lkl: add dhcp client option

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Merge pull request #1 from torvalds/master #275

Merge pull request #1 from torvalds/master #275

nanszy commented Apr 13, 2016

Merge pull request #1 from torvalds/master #275

Merge pull request #1 from torvalds/master #275

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nanszy commented Apr 13, 2016