syzbot


INFO: task hung in flush_workqueue

Status: fixed on 2019/01/11 01:22
Subsystems: media
[Documentation on labels]
Reported-by: syzbot+69780d144754b8071f4b@syzkaller.appspotmail.com
Fix commit: 52117be68b82 media: vim2m: use cancel_delayed_work_sync instead of flush_schedule_work
First crash: 2030d, last: 1979d
Discussions (6)
Title Replies (including bot) Last reply
[PATCH 4.19 000/190] 4.19.73-stable review 207 (207) 2019/09/16 09:25
[PATCH AUTOSEL 4.19 001/167] drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse" 195 (195) 2019/09/15 15:19
[PATCH 4.20 000/145] 4.20.1-stable review 164 (164) 2019/01/09 23:18
[GIT PULL FOR v4.18] v2: Various fixes/improvements 4 (4) 2018/11/22 22:43
[PATCH] vim2m: use cancel_delayed_work_sync instead of flush_schedule_work 2 (2) 2018/11/22 21:30
INFO: task hung in flush_workqueue 0 (2) 2018/11/04 07:39
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in flush_workqueue (2) afs net 2 1884d 1892d 0/26 auto-closed as invalid on 2019/09/24 07:48

Sample crash report:
audit: type=1400 audit(1541599844.544:36): avc:  denied  { map } for  pid=5838 comm="syz-executor611" path="/root/syz-executor611813425" dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
INFO: task syz-executor611:5839 blocked for more than 140 seconds.
      Not tainted 4.20.0-rc1+ #102
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor611 D24216  5839   5838 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2831 [inline]
 __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472
 schedule+0xfe/0x460 kernel/sched/core.c:3516
 schedule_timeout+0x1cc/0x260 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+0x427/0x8a0 kernel/sched/completion.c:136
 flush_workqueue+0x742/0x1e10 kernel/workqueue.c:2707
 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
RIP: 0033:0x401010
Code: 00 00 00 00 00 00 00 00 00 00 c4 04 00 00 12 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 cd 01 00 00 12 00 00 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 00 00 12 00
RSP: 002b:00007fff234b5948 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000401010
RDX: 0000000000444bb9 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00000000004002e0 R09: 00000000004002e0
R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000401f20
R13: 0000000000401fb0 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1007:
 #0: 000000002e0331b1 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379
2 locks held by kworker/0:2/2881:
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:209 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: 00000000078d9039 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb43/0x1c40 kernel/workqueue.c:2124
 #1: 00000000f078aaa2 ((work_completion)(&smc->tcp_listen_work)){+.+.}, at: process_one_work+0xb9a/0x1c40 kernel/workqueue.c:2128
1 lock held by rsyslogd/5687:
 #0: 00000000c647e6e7 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766
2 locks held by getty/5810:
 #0: 000000003d7d6040 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 000000008ac92458 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5811:
 #0: 000000009b7104d4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 0000000016c3d5ed (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5812:
 #0: 000000009123291c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 00000000aea2787f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5813:
 #0: 00000000992b284e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 000000009bdfd77d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5814:
 #0: 00000000837c3129 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 00000000c2dc8f22 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5815:
 #0: 0000000045e1641d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 00000000cadbf83b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5816:
 #0: 00000000f27b6290 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
 #1: 0000000084a243bb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by syz-executor611/5839:
 #0: 00000000356ef51e (&mdev->req_queue_mutex){+.+.}, at: v4l2_release+0x1d7/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:455
 #1: 000000006a8dd9f3 (&dev->dev_mutex){+.+.}, at: vim2m_release+0xbc/0x150 drivers/media/platform/vim2m.c:976

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1007 Comm: khungtaskd Not tainted 4.20.0-rc1+ #102
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+0x244/0x39d lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1e8/0x22a 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:144 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xb51/0x1060 kernel/hung_task.c:289
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57

Crashes (293):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/11/07 14:16 upstream 8053e5b93eca 8bd6bd63 .config console log report syz C ci-upstream-kasan-gce-selinux-root
2018/11/06 17:27 upstream 163c8d54a997 8bd6bd63 .config console log report syz C ci-upstream-kasan-gce-root
2018/11/05 09:35 upstream 4710e78940d8 8bd6bd63 .config console log report syz C ci-upstream-kasan-gce
2018/11/04 07:38 upstream d2ff0ff2c23f 8bd6bd63 .config console log report syz C ci-upstream-kasan-gce-smack-root
2018/11/05 09:47 upstream 4710e78940d8 8bd6bd63 .config console log report syz C ci-upstream-kasan-gce-386
2018/12/22 22:22 upstream 23203e3f34c9 e3bd7ab8 .config console log report ci-upstream-kasan-gce
2018/12/20 13:36 upstream ab63e725b49c aaf59e84 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/20 04:38 upstream ab63e725b49c 02e69052 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/19 23:57 upstream 62393dbcbe0f 02e69052 .config console log report ci-upstream-kasan-gce-root
2018/12/19 12:11 upstream 62393dbcbe0f fe2dc057 .config console log report ci-upstream-kasan-gce
2018/12/19 01:23 upstream ddfbab46539f 4edaba93 .config console log report ci-upstream-kasan-gce
2018/12/18 11:09 upstream 1a9430db2835 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/18 02:30 upstream 1a9430db2835 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/18 00:37 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/17 21:46 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/17 19:43 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/17 17:28 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce-root
2018/12/17 11:07 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/17 09:10 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce
2018/12/17 01:40 upstream 7566ec393f41 def91db3 .config console log report ci-upstream-kasan-gce-root
2018/12/16 20:12 upstream 6531e115b7ab def91db3 .config console log report ci-upstream-kasan-gce
2018/12/16 18:49 upstream 6531e115b7ab def91db3 .config console log report ci-upstream-kasan-gce
2018/12/16 10:59 upstream 6531e115b7ab def91db3 .config console log report ci-upstream-kasan-gce
2018/12/16 08:28 upstream 6531e115b7ab def91db3 .config console log report ci-upstream-kasan-gce
2018/12/16 01:57 upstream 6531e115b7ab def91db3 .config console log report ci-upstream-kasan-gce
2018/12/14 19:29 upstream eb6cf9f8cb9d 7624ddd6 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/14 17:10 upstream 65e08c5e8631 7624ddd6 .config console log report ci-upstream-kasan-gce
2018/12/14 13:15 upstream 65e08c5e8631 7624ddd6 .config console log report ci-upstream-kasan-gce-smack-root
2018/12/14 03:44 upstream 65e08c5e8631 fe7127be .config console log report ci-upstream-kasan-gce
2018/12/13 18:14 upstream f5d582777bcb f3d9d594 .config console log report ci-upstream-kasan-gce
2018/12/12 22:48 upstream f5d582777bcb 02613a41 .config console log report ci-upstream-kasan-gce
2018/12/12 08:57 upstream f5d582777bcb 7795ae03 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/12 06:00 upstream f5d582777bcb 7795ae03 .config console log report ci-upstream-kasan-gce-smack-root
2018/12/11 13:07 upstream f5d582777bcb 7795ae03 .config console log report ci-upstream-kasan-gce
2018/12/11 12:03 upstream f5d582777bcb 7795ae03 .config console log report ci-upstream-kasan-gce
2018/12/11 01:19 upstream f5d582777bcb 4093e33b .config console log report ci-upstream-kasan-gce
2018/12/10 12:52 upstream 40e020c129cf 6565f24d .config console log report ci-upstream-kasan-gce
2018/12/09 23:49 upstream 0844895a2e51 96cc4c50 .config console log report ci-upstream-kasan-gce-selinux-root
2018/12/09 12:27 upstream 8214bdf7d3e6 979179d6 .config console log report ci-upstream-kasan-gce-smack-root
2018/12/08 23:59 upstream 8214bdf7d3e6 c7918378 .config console log report ci-upstream-kasan-gce-root
2018/12/08 21:53 upstream 8214bdf7d3e6 60562a1d .config console log report ci-upstream-kasan-gce-smack-root
2018/12/08 12:03 upstream 5f179793f0a7 60562a1d .config console log report ci-upstream-kasan-gce
2018/12/19 09:58 upstream 62393dbcbe0f 4edaba93 .config console log report ci-upstream-kasan-gce-386
2018/12/19 08:12 upstream 62393dbcbe0f 4edaba93 .config console log report ci-upstream-kasan-gce-386
2018/12/18 12:52 upstream 1a9430db2835 4edaba93 .config console log report ci-upstream-kasan-gce-386
2018/12/15 09:48 upstream 6531e115b7ab c9128939 .config console log report ci-upstream-kasan-gce-386
2018/12/15 08:36 upstream 6531e115b7ab c9128939 .config console log report ci-upstream-kasan-gce-386
2018/12/15 06:22 upstream eb6cf9f8cb9d 7624ddd6 .config console log report ci-upstream-kasan-gce-386
2018/12/13 22:57 upstream 65e08c5e8631 fe7127be .config console log report ci-upstream-kasan-gce-386
2018/12/12 18:47 upstream f5d582777bcb c3b10a5d .config console log report ci-upstream-kasan-gce-386
2018/12/10 01:07 upstream 0844895a2e51 96cc4c50 .config console log report ci-upstream-kasan-gce-386
2018/12/02 11:06 linux-next 442b8cea2477 e0d8c853 .config console log report ci-upstream-linux-next-kasan-gce-root
2018/11/01 12:20 linux-next 4db9d11bcbef 1f38e9ae .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.