6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr
[ Upstream commit fe48ba7daefe75bbbefa2426deddc05f2d530d2d ]
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.uni... Signed-off-by: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/workqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 800b4208dba9a..e51ab3d4765eb 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2569,6 +2569,7 @@ __acquires(&pool->lock) */ set_work_pool_and_clear_pending(work, pool->id);
+ pwq->stats[PWQ_STAT_STARTED]++; raw_spin_unlock_irq(&pool->lock);
lock_map_acquire(&pwq->wq->lockdep_map); @@ -2595,7 +2596,6 @@ __acquires(&pool->lock) * workqueues), so hiding them isn't a problem. */ lockdep_invariant_state(true); - pwq->stats[PWQ_STAT_STARTED]++; trace_workqueue_execute_start(work); worker->current_func(work); /*