syzbot
possible deadlock in v4l2_release
Status:
auto-obsoleted due to no activity on 2022/09/03 06:25
Subsystems:
media
[Documentation on labels]
Reported-by: syzbot+ea05c832a73d0615bf33@syzkaller.appspotmail.com
First crash: 2814d, last: 2773d
Fix bisection: fixed by
(bisect log) [no-op commit]:
commit b53119f13a04879c3bf502828d99d13726639ead
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Mar 7 01:22:54 2019 +0000
pin iocb through aio.
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Last patch testing requests (6)
| Created |
Duration |
User |
Patch |
Repo |
Result |
| 2022/09/03 01:27 |
19m
|
retest repro
|
|
upstream |
OK
log
|
| 2022/09/01 12:27 |
16m
|
retest repro
|
|
linux-next |
OK
log
|
| 2022/09/01 10:27 |
16m
|
retest repro
|
|
upstream |
OK
log
|
| 2022/08/31 16:27 |
18m
|
retest repro
|
|
upstream |
OK
log
|
| 2022/08/31 14:27 |
16m
|
retest repro
|
|
upstream |
OK
log
|
| 2022/08/31 02:27 |
17m
|
retest repro
|
|
upstream |
OK
log
|
Sample crash report:
audit: type=1800 audit(1542499591.861:30): pid=5853 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0
======================================================
WARNING: possible circular locking dependency detected
4.20.0-rc2+ #338 Not tainted
------------------------------------------------------
kworker/0:1/12 is trying to acquire lock:
00000000568502c5 (&mdev->req_queue_mutex){+.+.}, at: v4l2_release+0x1d7/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:455
but task is already holding lock:
000000009d901cd4 ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40 kernel/workqueue.c:2128
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 ((delayed_fput_work).work){+.+.}:
process_one_work+0xc0a/0x1c40 kernel/workqueue.c:2129
worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
-> #2 ((wq_completion)"events"){+.+.}:
flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655
flush_scheduled_work include/linux/workqueue.h:599 [inline]
vim2m_stop_streaming+0x7c/0x2c0 drivers/media/platform/vim2m.c:811
__vb2_queue_cancel+0x171/0xd20 drivers/media/common/videobuf2/videobuf2-core.c:1823
vb2_core_queue_release+0x26/0x80 drivers/media/common/videobuf2/videobuf2-core.c:2229
vb2_queue_release+0x15/0x20 drivers/media/common/videobuf2/videobuf2-v4l2.c:837
v4l2_m2m_ctx_release+0x1e/0x35 drivers/media/v4l2-core/v4l2-mem2mem.c:930
vim2m_release+0xe6/0x150 drivers/media/platform/vim2m.c:977
v4l2_release+0x224/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:456
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (&dev->dev_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x166/0x16f0 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
vim2m_release+0xbc/0x150 drivers/media/platform/vim2m.c:976
v4l2_release+0x224/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:456
__fput+0x385/0xa30 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&mdev->req_queue_mutex){+.+.}:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x166/0x16f0 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
v4l2_release+0x1d7/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:455
__fput+0x385/0xa30 fs/file_table.c:278
delayed_fput+0x55/0x80 fs/file_table.c:304
process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
other info that might help us debug this:
Chain exists of:
&mdev->req_queue_mutex --> (wq_completion)"events" --> (delayed_fput_work).work
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock((delayed_fput_work).work);
lock((wq_completion)"events");
lock((delayed_fput_work).work);
lock(&mdev->req_queue_mutex);
*** DEADLOCK ***
2 locks held by kworker/0:1/12:
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:209 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: 00000000809bd6ac ((wq_completion)"events"){+.+.}, at: process_one_work+0xb43/0x1c40 kernel/workqueue.c:2124
#1: 000000009d901cd4 ((delayed_fput_work).work){+.+.}, at: process_one_work+0xb9a/0x1c40 kernel/workqueue.c:2128
stack backtrace:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 4.20.0-rc2+ #338
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events delayed_fput
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
print_circular_bug.isra.35.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221
check_prev_add kernel/locking/lockdep.c:1863 [inline]
check_prevs_add kernel/locking/lockdep.c:1976 [inline]
validate_chain kernel/locking/lockdep.c:2347 [inline]
__lock_acquire+0x3399/0x4c20 kernel/locking/lockdep.c:3341
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x166/0x16f0 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
v4l2_release+0x1d7/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:455
__fput+0x385/0xa30 fs/file_table.c:278
delayed_fput+0x55/0x80 fs/file_table.c:304
process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Struck through repros no longer work on HEAD.