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| Kernel | Title | Rank 🛈 | Repro | Cause bisect | Fix bisect | Count | Last | Reported | Patched | Status |
|---|---|---|---|---|---|---|---|---|---|---|
| upstream | possible deadlock in refcount_dec_and_mutex_lock nbd | 4 | 1 | 2365d | 2361d | 0/29 | auto-closed as invalid on 2019/11/20 04:39 | |||
| linux-4.19 | possible deadlock in refcount_dec_and_mutex_lock | 4 | C | done | done | 5 | 2266d | 2321d | 1/1 | fixed on 2020/01/28 16:29 |
| upstream | possible deadlock in refcount_dec_and_mutex_lock (2) perf | 4 | C | 5 | 6h40m | 6d04h | 0/29 | upstream: reported C repro on 2026/03/07 06:53 |
block nbd0: shutting down sockets
block nbd0: Receive control failed (result -22)
block nbd0: shutting down sockets
block nbd0: Receive control failed (result -22)
======================================================
WARNING: possible circular locking dependency detected
4.14.151 #0 Not tainted
------------------------------------------------------
kworker/u5:0/1143 is trying to acquire lock:
(&nbd->config_lock){+.+.}, at: [<ffffffff82d77ed9>] refcount_dec_and_mutex_lock lib/refcount.c:312 [inline]
(&nbd->config_lock){+.+.}, at: [<ffffffff82d77ed9>] refcount_dec_and_mutex_lock+0x49/0x6c lib/refcount.c:307
but task is already holding lock:
((&args->work)){+.+.}, at: [<ffffffff813cf92b>] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 ((&args->work)){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
process_one_work+0x803/0x1600 kernel/workqueue.c:2090
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
-> #1 ("knbd%d-recv"nbd->index){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
flush_workqueue+0x109/0x1400 kernel/workqueue.c:2616
drain_workqueue+0x177/0x3e0 kernel/workqueue.c:2781
destroy_workqueue+0x21/0x620 kernel/workqueue.c:4088
nbd_config_put+0x43c/0x7a0 drivers/block/nbd.c:1124
nbd_release+0xdb/0x120 drivers/block/nbd.c:1393
__blkdev_put+0x434/0x7f0 fs/block_dev.c:1791
blkdev_put+0x88/0x510 fs/block_dev.c:1856
blkdev_close+0x8b/0xb0 fs/block_dev.c:1863
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x7df/0x2c10 kernel/exit.c:874
do_group_exit+0x111/0x330 kernel/exit.c:977
SYSC_exit_group kernel/exit.c:988 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:986
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
-> #0 (&nbd->config_lock){+.+.}:
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
refcount_dec_and_mutex_lock lib/refcount.c:312 [inline]
refcount_dec_and_mutex_lock+0x49/0x6c lib/refcount.c:307
nbd_config_put+0x31/0x7a0 drivers/block/nbd.c:1102
recv_work+0x18d/0x1f0 drivers/block/nbd.c:724
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
other info that might help us debug this:
Chain exists of:
&nbd->config_lock --> "knbd%d-recv"nbd->index --> (&args->work)
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock((&args->work));
lock("knbd%d-recv"nbd->index);
lock((&args->work));
lock(&nbd->config_lock);
*** DEADLOCK ***
2 locks held by kworker/u5:0/1143:
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813cf8ee>] work_static include/linux/workqueue.h:199 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813cf8ee>] set_work_data kernel/workqueue.c:619 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813cf8ee>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
#0: ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff813cf8ee>] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085
#1: ((&args->work)){+.+.}, at: [<ffffffff813cf92b>] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089
stack backtrace:
CPU: 0 PID: 1143 Comm: kworker/u5:0 Not tainted 4.14.151 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: knbd0-recv recv_work
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x197 lib/dump_stack.c:53
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
refcount_dec_and_mutex_lock lib/refcount.c:312 [inline]
refcount_dec_and_mutex_lock+0x49/0x6c lib/refcount.c:307
nbd_config_put+0x31/0x7a0 drivers/block/nbd.c:1102
recv_work+0x18d/0x1f0 drivers/block/nbd.c:724
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
block nbd0: shutting down sockets