INFO: task syz-executor0:10118 blocked for more than 140 seconds. Not tainted 4.20.0-rc7+ #383 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D22936 10118 6017 0x00000004 Call Trace: context_switch kernel/sched/core.c:2831 [inline] __schedule+0x86c/0x1ed0 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+0x14f/0xd50 drivers/media/common/videobuf2/videobuf2-core.c:1843 vb2_core_streamoff+0x60/0x140 drivers/media/common/videobuf2/videobuf2-core.c:2006 vb2_streamoff+0x4a/0x90 drivers/media/common/videobuf2/videobuf2-v4l2.c:789 v4l2_m2m_streamoff+0xd0/0x720 drivers/media/v4l2-core/v4l2-mem2mem.c:563 v4l2_m2m_ioctl_streamoff+0x6b/0x80 drivers/media/v4l2-core/v4l2-mem2mem.c:1081 v4l_streamoff+0x76/0x90 drivers/media/v4l2-core/v4l2-ioctl.c:1698 __video_do_ioctl+0x8b1/0x1050 drivers/media/v4l2-core/v4l2-ioctl.c:2853 video_usercopy+0x5c1/0x1760 drivers/media/v4l2-core/v4l2-ioctl.c:3035 video_ioctl2+0x2c/0x33 drivers/media/v4l2-core/v4l2-ioctl.c:3079 v4l2_ioctl+0x154/0x1b0 drivers/media/v4l2-core/v4l2-dev.c:364 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457669 Code: 27 fc ff e8 39 78 fc ff 48 8b 44 24 08 e9 95 fe ff ff e8 5a 28 00 00 e9 45 fe ff ff cc cc cc cc cc 48 8b 4c 24 10 48 8b 11 64 <48> 8b 1c 25 f8 ff ff ff 8b b2 d8 00 00 00 8d 7e ff 89 ba d8 00 00 RSP: 002b:00007f2da38c0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457669 RDX: 0000000020000080 RSI: 0000000040045613 RDI: 0000000000000006 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2da38c16d4 R13: 00000000004c1fe7 R14: 00000000004d3c48 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1018: #0: 00000000df54c338 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379 4 locks held by rs:main Q:Reg/5882: #0: 00000000f64bd7bc (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9678 [inline] #0: 00000000f64bd7bc (&rq->lock){-.-.}, at: pick_next_task_fair+0x1336/0x1b40 kernel/sched/fair.c:6757 #1: 00000000df54c338 (rcu_read_lock){....}, at: perf_iterate_sb+0x0/0xc60 kernel/events/core.c:4179 #2: 0000000031c525c5 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:777 [inline] #2: 0000000031c525c5 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x2a1/0x1420 fs/ext4/file.c:232 #3: 00000000df54c338 (rcu_read_lock){....}, at: inode_cgwb_enabled include/linux/backing-dev.h:254 [inline] #3: 00000000df54c338 (rcu_read_lock){....}, at: balance_dirty_pages_ratelimited+0x7db/0x23a0 mm/page-writeback.c:1872 1 lock held by rsyslogd/5884: 2 locks held by getty/5975: #0: 0000000031f0d09b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000005c3bac4f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5976: #0: 0000000021ad1d2a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000005235c54 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5977: #0: 0000000045131ac2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000384419c5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5978: #0: 000000008ca1f098 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000003eb69934 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5979: #0: 00000000434ec94a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000e5c1f91 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5980: #0: 00000000bd5511e8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000bc2cafd5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 2 locks held by getty/5981: #0: 000000006b1ca597 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000003c1b8912 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154 3 locks held by kworker/0:2/6116: #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:218 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000006cdcd610 ((wq_completion)"events"){+.+.}, at: process_one_work+0xb43/0x1c40 kernel/workqueue.c:2124 #1: 000000003e32b501 ((work_completion)(&smc->tcp_listen_work)){+.+.}, at: process_one_work+0xb9a/0x1c40 kernel/workqueue.c:2128 #2: 00000000d762e1d9 (&smc->clcsock_release_lock){+.+.}, at: smc_clcsock_accept net/smc/af_smc.c:844 [inline] #2: 00000000d762e1d9 (&smc->clcsock_release_lock){+.+.}, at: smc_tcp_listen_work+0x200/0x1140 net/smc/af_smc.c:1315 2 locks held by syz-executor0/10118: #0: 0000000040462b0a (&mdev->req_queue_mutex){+.+.}, at: __video_do_ioctl+0xb6c/0x1050 drivers/media/v4l2-core/v4l2-ioctl.c:2815 #1: 00000000236cad8f (&dev->dev_mutex){+.+.}, at: __video_do_ioctl+0x461/0x1050 drivers/media/v4l2-core/v4l2-ioctl.c:2821 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1018 Comm: khungtaskd Not tainted 4.20.0-rc7+ #383 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+0x1d3/0x2c6 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1c2/0x22c 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: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