INFO: task syz-executor.3:8832 blocked for more than 140 seconds. Not tainted 4.14.151 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28528 8832 6931 0x00000004 Call Trace: context_switch kernel/sched/core.c:2807 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3383 schedule+0x92/0x1c0 kernel/sched/core.c:3427 schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144 kthread_stop+0xda/0x650 kernel/kthread.c:530 vivid_stop_generating_vid_cap+0x1b9/0x664 drivers/media/platform/vivid/vivid-kthread-cap.c:934 vid_cap_stop_streaming+0x7c/0xd0 drivers/media/platform/vivid/vivid-vid-cap.c:273 __vb2_queue_cancel+0xa3/0x890 drivers/media/v4l2-core/videobuf2-core.c:1655 vb2_core_streamoff+0x52/0x110 drivers/media/v4l2-core/videobuf2-core.c:1788 __vb2_cleanup_fileio+0x78/0x150 drivers/media/v4l2-core/videobuf2-core.c:2313 vb2_core_queue_release+0x1d/0x80 drivers/media/v4l2-core/videobuf2-core.c:2040 vb2_queue_release drivers/media/v4l2-core/videobuf2-v4l2.c:669 [inline] _vb2_fop_release+0x1cf/0x2a0 drivers/media/v4l2-core/videobuf2-v4l2.c:840 vb2_fop_release+0x75/0xc0 drivers/media/v4l2-core/videobuf2-v4l2.c:854 vivid_fop_release+0x180/0x3f0 drivers/media/platform/vivid/vivid-core.c:486 v4l2_release+0xf9/0x190 drivers/media/v4l2-core/v4l2-dev.c:446 __fput+0x275/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x114/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a219 RSP: 002b:00007f56b26dec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 000000000045a219 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f56b26df6d4 R13: 00000000004faf72 R14: 00000000004d3238 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1016: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 1 lock held by rsyslogd/6762: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xab/0xd0 fs/file.c:769 2 locks held by getty/6884: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6885: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6886: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6887: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6888: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6889: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6890: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1016 Comm: khungtaskd Not tainted 4.14.151 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x138/0x197 lib/dump_stack.c:53 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6760 Comm: rs:main Q:Reg Not tainted 4.14.151 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880901083c0 task.stack: ffff8880913a0000 RIP: 0010:blk_flush_queue_rq+0x0/0x2d0 block/blk-flush.c:136 RSP: 0018:ffff8880913a7608 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffff88809e2a6dc0 RCX: 1ffff110143d3c18 RDX: 1ffff110143e2d96 RSI: 0000000000000000 RDI: ffff8880a1f16b80 RBP: ffff8880913a7658 R08: 000000650b66d6a1 R09: ffff88821fff8048 R10: ffff88821fff8050 R11: 0000000000000001 R12: ffff8880a1f16b80 R13: ffff8880a4f2e900 R14: 0000000000000001 R15: ffff8880a1dc8680 FS: 00007f6e98e54700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c42010c000 CR3: 0000000098700000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: blk_insert_flush+0x4ab/0x8e0 block/blk-flush.c:484 blk_mq_sched_insert_flush block/blk-mq-sched.c:352 [inline] blk_mq_sched_insert_request+0x48f/0x5a0 block/blk-mq-sched.c:367 blk_mq_make_request+0x52e/0x1c10 block/blk-mq.c:1750 generic_make_request block/blk-core.c:2227 [inline] generic_make_request+0x205/0xa40 block/blk-core.c:2171 submit_bio+0x1a5/0x3f0 block/blk-core.c:2301 submit_bio_wait+0x108/0x160 block/bio.c:1012 blkdev_issue_flush+0x22a/0x330 block/blk-flush.c:531 ext4_sync_file+0xa78/0x12d0 fs/ext4/fsync.c:157 vfs_fsync_range+0x10e/0x260 fs/sync.c:196 generic_write_sync include/linux/fs.h:2677 [inline] ext4_file_write_iter+0x68a/0xe90 fs/ext4/file.c:279 call_write_iter include/linux/fs.h:1777 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x4a7/0x6b0 fs/read_write.c:482 vfs_write+0x198/0x500 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xfd/0x230 fs/read_write.c:582 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f6e9a8b219d RSP: 002b:00007f6e98e52f90 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000400 RCX: 00007f6e9a8b219d RDX: 0000000000000400 RSI: 000000000125ace0 RDI: 0000000000000007 RBP: 000000000125ace0 R08: 2032303a37303a33 R09: 656c6c616b7a7973 R10: 6c656e72656b2072 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f6e98e53410 R14: 00007f6e90000e10 R15: 000000000125aae0 Code: 75 1a 49 8b b7 a0 00 00 00 48 c7 c7 a0 cc 9b 86 e8 09 e6 83 fe 0f 0b e9 cc fa ff ff e8 8a 5c bf fe eb df 90 90 90 90 90 90 90 90 <55> 48 89 e5 41 56 41 55 41 54 49 89 fc 53 89 f3 e8 4b aa 95 fe