Hello,
syzbot found the following crash on:
HEAD commit: 4d552acf Linux 4.19.34
git tree: linux-4.19.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=16cb729f200000
kernel config:
https://syzkaller.appspot.com/x/.config?x=c95a88291f095edd
dashboard link:
https://syzkaller.appspot.com/bug?extid=3774865aab936ee8e875
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
Unfortunately, I don't have any reproducer for this crash yet.
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by:
syzbot+377486...@syzkaller.appspotmail.com
INFO: task syz-executor.3:9957 blocked for more than 140 seconds.
Not tainted 4.19.34 #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D28216 9957 8036 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2826 [inline]
__schedule+0x817/0x1d00 kernel/sched/core.c:3474
schedule+0x92/0x1c0 kernel/sched/core.c:3518
schedule_timeout+0x8ca/0xfd0 kernel/time/timer.c:1780
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136
kthread_stop+0x116/0x6d0 kernel/kthread.c:550
sdr_cap_stop_streaming+0x213/0x330
drivers/media/platform/vivid/vivid-sdr-cap.c:301
__vb2_queue_cancel+0xb4/0x970
drivers/media/common/videobuf2/videobuf2-core.c:1662
vb2_core_streamoff+0x60/0x140
drivers/media/common/videobuf2/videobuf2-core.c:1796
__vb2_cleanup_fileio+0x78/0x170
drivers/media/common/videobuf2/videobuf2-core.c:2323
vb2_core_queue_release+0x20/0x80
drivers/media/common/videobuf2/videobuf2-core.c:2050
vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:671
[inline]
_vb2_fop_release+0x1cf/0x2a0
drivers/media/common/videobuf2/videobuf2-v4l2.c:842
vb2_fop_release+0x75/0xc0
drivers/media/common/videobuf2/videobuf2-v4l2.c:856
vivid_fop_release+0x18e/0x430 drivers/media/platform/vivid/vivid-core.c:474
v4l2_release+0xfb/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:448
__fput+0x2df/0x8b0 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x14a/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x273/0x2c0 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+0x52d/0x610 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4120b1
Code: 00 74 1b 48 83 ec 08 e8 ed 8e ff ff 48 c7 05 d2 b5 24 00 00 00 00 00
31 c0 48 83 c4 08 c3 31 c0 c3 0f 1f 84 00 00 00 00 00 48 <83> ec 08 b9 40
96 65 00 31 d2 be 53 25 44 00 bf 52 37 44 00 ff 15
RSP: 002b:00007fffdb3bd170 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00000000004120b1
RDX: 0000000000000000 RSI: 00000000007402c0 RDI: 0000000000000005
RBP: 000000000073c900 R08: ffffffff812f902a R09: 00000000ffc15122
R10: 00007fffdb3bd240 R11: 0000000000000293 R12: ffffffffffffffff
R13: 000000000001d1b1 R14: 00000000000003e8 R15: 000000000073bf0c
Showing all locks held in the system:
2 locks held by kworker/u4:3/981:
#0: 00000000be3e5631 (&rq->lock){-.-.}, at: idle_balance
kernel/sched/fair.c:9563 [inline]
#0: 00000000be3e5631 (&rq->lock){-.-.}, at:
pick_next_task_fair+0xaf6/0x1550 kernel/sched/fair.c:6749
#1: 000000008165dbce (rcu_read_lock){....}, at:
__update_idle_core+0x45/0x3f0 kernel/sched/fair.c:5966
1 lock held by khungtaskd/1033:
#0: 000000008165dbce (rcu_read_lock){....}, at:
debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438
1 lock held by rsyslogd/7861:
#0: 00000000bb22c494 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
fs/file.c:767
2 locks held by getty/7983:
#0: 000000002f5476cc (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 00000000e209d710 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7984:
#0: 00000000bf81698d (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 000000000faf75f2 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7985:
#0: 000000007d15a83a (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 00000000fa53597c (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7986:
#0: 000000003fb0ae30 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 000000005d60c398 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7987:
#0: 00000000fc4a86d9 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 000000004656e2ad (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7988:
#0: 000000008a4610bb (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 0000000043a6484e (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7989:
#0: 000000002ae30bf7 (&tty->ldisc_sem){++++}, at:
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
#1: 0000000001559e6d (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 1033 Comm: khungtaskd Not tainted 4.19.34 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:202 [inline]
watchdog+0x9c6/0xec0 kernel/hung_task.c:263
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 981 Comm: kworker/u4:3 Not tainted 4.19.34 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__trace_hardirqs_on_caller kernel/locking/lockdep.c:2837 [inline]
RIP: 0010:lockdep_hardirqs_on+0x1f5/0x5d0 kernel/locking/lockdep.c:2879
Code: 8b 83 68 08 00 00 85 c0 0f 85 2f 02 00 00 48 8d bb 30 08 00 00 48 b8
00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 87 03 00
00 48 8d bb 28 08 00 00 4c 89 a3 30 08 00 00 48 b8
RSP: 0018:ffff8880a8127bc0 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff8880a8118680 RCX: 1ffff110150231e9
RDX: 1ffff110150231d6 RSI: ffff8880a8118f28 RDI: ffff8880a8118eb0
RBP: ffff8880a8127bd0 R08: ffff8880a8118680 R09: ffff8880a8118f48
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8140a0da
R13: ffffffff86eedbb1 R14: ffffffff8140a0da R15: 0000000000000023
FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000000a0d43000 CR4: 00000000001406e0
Call Trace:
trace_hardirqs_on+0x67/0x230 kernel/trace/trace_preemptirq.c:30
__local_bh_enable_ip+0x15a/0x270 kernel/softirq.c:194
__raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
_raw_spin_unlock_bh+0x31/0x40 kernel/locking/spinlock.c:200
spin_unlock_bh include/linux/spinlock.h:374 [inline]
batadv_nc_purge_paths+0x267/0x370 net/batman-adv/network-coding.c:482
batadv_nc_worker+0x2cf/0x760 net/batman-adv/network-coding.c:733
process_one_work+0x98e/0x1760 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
---
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