INFO: task syz-executor.3:32348 blocked for more than 140 seconds. Not tainted 4.19.85-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28216 32348 7933 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: 0033:0x4141d1 Code: e9 58 03 00 00 48 8b 1b 48 85 db 0f 84 eb 01 00 00 48 89 5c 24 28 8b 73 58 8d 41 fe 39 c6 75 15 8d 71 ff f0 0f b1 73 58 40 0f <94> c6 40 84 f6 0f 85 6c 01 00 00 8b 73 58 8d 79 ff 39 fe 74 c6 48 RSP: 002b:00007fffcfcb1610 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00000000004141d1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000001 R08: 00000000feecbb36 R09: 00000000feecbb3a R10: 00007fffcfcb16f0 R11: 0000000000000293 R12: 000000000075c9a0 R13: 000000000075c9a0 R14: 0000000000760a50 R15: 000000000075bf2c Showing all locks held in the system: 2 locks held by kworker/u4:4/489: #0: 000000008fefa13c (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9591 [inline] #0: 000000008fefa13c (&rq->lock){-.-.}, at: pick_next_task_fair+0xfae/0x1580 kernel/sched/fair.c:6772 #1: 000000002b4e8944 (rcu_read_lock){....}, at: __update_idle_core+0x45/0x3f0 kernel/sched/fair.c:5989 1 lock held by khungtaskd/1040: #0: 000000002b4e8944 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438 2 locks held by rsyslogd/7551: #0: 00000000fe9173b5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767 #1: 00000000777e19ce (&obj_hash[i].lock){-.-.}, at: double_lock_hb kernel/futex.c:1559 [inline] #1: 00000000777e19ce (&obj_hash[i].lock){-.-.}, at: futex_wake_op kernel/futex.c:1696 [inline] #1: 00000000777e19ce (&obj_hash[i].lock){-.-.}, at: do_futex+0x9e3/0x1d70 kernel/futex.c:3657 2 locks held by getty/7673: #0: 0000000026624d9e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000ee3ae657 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7674: #0: 00000000503431e0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000b83ec5d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7675: #0: 000000009b66203a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000d565af1f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7676: #0: 0000000073acfc32 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000058be6bd2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7677: #0: 00000000ef7dd222 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000003c0fb38d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7678: #0: 00000000b7cee594 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000b390bcd8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7679: #0: 0000000039bd9144 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000a73311a7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1040 Comm: khungtaskd Not tainted 4.19.85-syzkaller #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+0x197/0x210 lib/dump_stack.c:118 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 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60