INFO: task syz-executor.4:26783 blocked for more than 140 seconds. Not tainted 4.19.79 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28216 26783 10032 0x00000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x866/0x1dc0 kernel/sched/core.c:3515 schedule+0x92/0x1c0 kernel/sched/core.c:3559 schedule_timeout+0x8c8/0xfc0 kernel/time/timer.c:1782 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+0x116/0x6c0 kernel/kthread.c:550 vivid_stop_generating_vid_cap+0x1e0/0x6e2 drivers/media/platform/vivid/vivid-kthread-cap.c:922 vid_cap_stop_streaming+0x8a/0xe0 drivers/media/platform/vivid/vivid-vid-cap.c:256 __vb2_queue_cancel+0xb1/0x790 drivers/media/common/videobuf2/videobuf2-core.c:1682 vb2_core_streamoff+0x60/0x150 drivers/media/common/videobuf2/videobuf2-core.c:1816 __vb2_cleanup_fileio+0x78/0x170 drivers/media/common/videobuf2/videobuf2-core.c:2343 vb2_core_queue_release+0x20/0x80 drivers/media/common/videobuf2/videobuf2-core.c:2070 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+0xf9/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:448 __fput+0x2dd/0x8b0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x145/0x1c0 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:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x413741 Code: 00 b8 2d f8 ff ff 0f 44 c2 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 31 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 48 c7 07 40 37 41 00 RSP: 002b:00007ffda378a1d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000413741 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000001 R08: 00000000f1b0d8d6 R09: 00000000f1b0d8da R10: 00007ffda378a2b0 R11: 0000000000000293 R12: 000000000075bf20 R13: 000000000009980f R14: 0000000000760b28 R15: 000000000075bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1037: #0: 00000000b33cb3de (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438 1 lock held by rsyslogd/7328: #0: 000000004eeb8c48 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767 2 locks held by getty/7451: #0: 000000003754c840 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000008867bd93 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7452: #0: 000000000c1ab3f1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000085139ac1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7453: #0: 0000000014bb008b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000e41c1e98 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7454: #0: 00000000d4d9c825 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000008a0300ab (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7455: #0: 00000000eea5c259 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000563168e2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7456: #0: 000000005de67c9b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000002b03663 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7457: #0: 00000000d1534a10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000050b25701 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1037 Comm: khungtaskd Not tainted 4.19.79 #0 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:203 [inline] watchdog+0x9df/0xee0 kernel/hung_task.c:287 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3587 Comm: udevd Not tainted 4.19.79 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lock_acquire+0x1f4/0x3f0 kernel/locking/lockdep.c:3907 Code: e8 03 80 3c 10 00 0f 85 c4 01 00 00 48 83 3d 0a 42 20 07 00 0f 84 38 01 00 00 48 8b 7d c8 57 9d 0f 1f 44 00 00 48 8d 65 d8 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 65 8b 05 cb 7c af 7e 83 f8 3f 0f 87 RSP: 0018:ffff888097cd7c88 EFLAGS: 00000082 RAX: 1ffffffff10e48c9 RBX: ffff888097e4d780 RCX: 00000000374ff10d RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000082 RBP: ffff888097cd7ca8 R08: 0000000000007668 R09: 0000000000000000 R10: ffff888097ccedc0 R11: ffffffff89e88800 R12: ffff888097e4d818 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f29255af7a0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000097c47000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160 spin_lock_irq include/linux/spinlock.h:354 [inline] ep_poll+0x1cf/0xd10 fs/eventpoll.c:1776 do_epoll_wait+0x1b3/0x200 fs/eventpoll.c:2198 __do_sys_epoll_wait fs/eventpoll.c:2208 [inline] __se_sys_epoll_wait fs/eventpoll.c:2205 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2205 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f2924cc3943 Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24 RSP: 002b:00007fff867f5df8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f2924cc3943 RDX: 0000000000000008 RSI: 00007fff867f5ef0 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000000be5170 R15: 0000000000bd1030