Messages in this thread | | | Date | Tue, 29 Aug 2023 09:52:51 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH v2 1/1] workqueue: fix data race with the pwq->stats[] increment |
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On Sat, Aug 26, 2023 at 04:51:03PM +0200, Mirsad Goran Todorovac wrote: > KCSAN has discovered a data race in kernel/workqueue.c:2598: > > [ 1863.554079] ================================================================== > [ 1863.554118] BUG: KCSAN: data-race in process_one_work / process_one_work > > [ 1863.554142] write to 0xffff963d99d79998 of 8 bytes by task 5394 on cpu 27: > [ 1863.554154] process_one_work (kernel/workqueue.c:2598) > [ 1863.554166] worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2752) > [ 1863.554177] kthread (kernel/kthread.c:389) > [ 1863.554186] ret_from_fork (arch/x86/kernel/process.c:145) > [ 1863.554197] ret_from_fork_asm (arch/x86/entry/entry_64.S:312) > > [ 1863.554213] read to 0xffff963d99d79998 of 8 bytes by task 5450 on cpu 12: > [ 1863.554224] process_one_work (kernel/workqueue.c:2598) > [ 1863.554235] worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2752) > [ 1863.554247] kthread (kernel/kthread.c:389) > [ 1863.554255] ret_from_fork (arch/x86/kernel/process.c:145) > [ 1863.554266] ret_from_fork_asm (arch/x86/entry/entry_64.S:312) > > [ 1863.554280] value changed: 0x0000000000001766 -> 0x000000000000176a > > [ 1863.554295] Reported by Kernel Concurrency Sanitizer on: > [ 1863.554303] CPU: 12 PID: 5450 Comm: kworker/u64:1 Tainted: G L 6.5.0-rc6+ #44 > [ 1863.554314] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023 > [ 1863.554322] Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] > [ 1863.554941] ================================================================== > > lockdep_invariant_state(true); > → pwq->stats[PWQ_STAT_STARTED]++; > trace_workqueue_execute_start(work); > worker->current_func(work); > > Moving pwq->stats[PWQ_STAT_STARTED]++; before the line > > raw_spin_unlock_irq(&pool->lock); > > resolves the data race without performance penalty. > > KCSAN detected at least one additional data race: > > [ 157.834751] ================================================================== > [ 157.834770] BUG: KCSAN: data-race in process_one_work / process_one_work > > [ 157.834793] write to 0xffff9934453f77a0 of 8 bytes by task 468 on cpu 29: > [ 157.834804] process_one_work (/home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2606) > [ 157.834815] worker_thread (/home/marvin/linux/kernel/linux_torvalds/./include/linux/list.h:292 /home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2752) > [ 157.834826] kthread (/home/marvin/linux/kernel/linux_torvalds/kernel/kthread.c:389) > [ 157.834834] ret_from_fork (/home/marvin/linux/kernel/linux_torvalds/arch/x86/kernel/process.c:145) > [ 157.834845] ret_from_fork_asm (/home/marvin/linux/kernel/linux_torvalds/arch/x86/entry/entry_64.S:312) > > [ 157.834859] read to 0xffff9934453f77a0 of 8 bytes by task 214 on cpu 7: > [ 157.834868] process_one_work (/home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2606) > [ 157.834879] worker_thread (/home/marvin/linux/kernel/linux_torvalds/./include/linux/list.h:292 /home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2752) > [ 157.834890] kthread (/home/marvin/linux/kernel/linux_torvalds/kernel/kthread.c:389) > [ 157.834897] ret_from_fork (/home/marvin/linux/kernel/linux_torvalds/arch/x86/kernel/process.c:145) > [ 157.834907] ret_from_fork_asm (/home/marvin/linux/kernel/linux_torvalds/arch/x86/entry/entry_64.S:312) > > [ 157.834920] value changed: 0x000000000000052a -> 0x0000000000000532 > > [ 157.834933] Reported by Kernel Concurrency Sanitizer on: > [ 157.834941] CPU: 7 PID: 214 Comm: kworker/u64:2 Tainted: G L 6.5.0-rc7-kcsan-00169-g81eaf55a60fc #4 > [ 157.834951] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023 > [ 157.834958] Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] > [ 157.835567] ================================================================== > > in code: > > trace_workqueue_execute_end(work, worker->current_func); > → pwq->stats[PWQ_STAT_COMPLETED]++; > lock_map_release(&lockdep_map); > lock_map_release(&pwq->wq->lockdep_map); > > which needs to be resolved separately. > > Fixes: 725e8ec59c56c ("workqueue: Add pwq->stats[] and a monitoring script") > Cc: Tejun Heo <tj@kernel.org> > Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com> > Link: https://lore.kernel.org/lkml/20230818194448.29672-1-mirsad.todorovac@alu.unizg.hr/ > Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Applied to wq/for-6.6.
Thanks.
-- tejun
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