kworker/dying (21) used greatest stack depth: 13720 bytes left INFO: task blkid:15837 blocked for more than 120 seconds. Not tainted 4.14.0-next-20171122+ #49 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. blkid D23696 15837 3117 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3492 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 blkdev_get+0x3a1/0xad0 fs/block_dev.c:1591 blkdev_open+0x1e4/0x270 fs/block_dev.c:1749 do_dentry_open+0x682/0xd70 fs/open.c:752 vfs_open+0x107/0x230 fs/open.c:866 do_last fs/namei.c:3388 [inline] path_openat+0x1157/0x3530 fs/namei.c:3528 do_filp_open+0x25b/0x3b0 fs/namei.c:3563 do_sys_open+0x502/0x6d0 fs/open.c:1059 SYSC_open fs/open.c:1077 [inline] SyS_open+0x2d/0x40 fs/open.c:1072 entry_SYSCALL_64_fastpath+0x1f/0x96 RIP: 0033:0x7f3788fb0120 RSP: 002b:00007fff03eb8148 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3788fb0120 RDX: 00007fff03eb8f34 RSI: 0000000000000000 RDI: 00007fff03eb8f34 RBP: 0000000000000086 R08: 0000000000000078 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001fde030 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000005 Showing all locks held in the system: 2 locks held by khungtaskd/672: #0: (rcu_read_lock){....}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554 2 locks held by getty/3022: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3023: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3024: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3025: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3026: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 2 locks held by getty/3027: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:7/3431: #0: ((wq_completion)"writeback"){+.+.}, at: [] __write_once_size include/linux/compiler.h:212 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] set_work_data kernel/workqueue.c:618 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:645 [inline] #0: ((wq_completion)"writeback"){+.+.}, at: [] process_one_work+0xad4/0x1be0 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [] process_one_work+0xb2f/0x1be0 kernel/workqueue.c:2087 #2: (&type->s_umount_key#31){++++}, at: [] trylock_super+0x20/0x100 fs/super.c:396 2 locks held by getty/10141: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131 1 lock held by syz-executor2/15809: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_put+0xa7/0x7c0 fs/block_dev.c:1757 1 lock held by blkid/15837: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor2/15913: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor2/15914: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 672 Comm: khungtaskd Not tainted 4.14.0-next-20171122+ #49 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+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3052 Comm: syz-fuzzer Not tainted 4.14.0-next-20171122+ #49 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801ccc7e240 task.stack: ffff8801bf088000 RIP: 0033:0x41f068 RSP: 002b:00007fbdfe330dc0 EFLAGS: 00000202 RAX: 000000c420060300 RBX: ffffffffff7348e8 RCX: 000000c42001c560 RDX: 0000000000000000 RSI: 000000c43b516800 RDI: 0000000000000005 RBP: 00007fbdfe330e00 R08: 000000000000003d R09: 000000000000003c R10: 0000000000000040 R11: 000000c423e161e0 R12: 0000000000000001 R13: 000000c44078a120 R14: 0000000000000001 R15: 0000000000000000 FS: 00007fbdfe331700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c43de21010 CR3: 00000001ccc2f000 CR4: 00000000001406e0