Buffer I/O error on dev loop6, logical block 16, async page read INFO: task blkid:7772 blocked for more than 120 seconds. Not tainted 4.14.0-rc7-next-20171103+ #38 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. blkid D20888 7772 1640 0x80000006 Call Trace: context_switch kernel/sched/core.c:2796 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3372 schedule+0xf5/0x430 kernel/sched/core.c:3431 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3489 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xadb/0x19d0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 blkdev_put+0x2a/0x4f0 fs/block_dev.c:1793 blkdev_close+0x91/0xc0 fs/block_dev.c:1842 __fput+0x333/0x7f0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9b5/0x1ad0 kernel/exit.c:869 do_group_exit+0x149/0x400 kernel/exit.c:972 get_signal+0x73f/0x16d0 kernel/signal.c:2333 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath+0x42f/0x510 arch/x86/entry/common.c:266 entry_SYSCALL_64_fastpath+0xbc/0xbe RIP: 0033:0x7fa92de4a310 RSP: 002b:00007ffdb4bdda08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: fffffffffffffffb RBX: 0000000000002000 RCX: 00007fa92de4a310 RDX: 0000000000000561 RSI: 0000000002126a58 RDI: 0000000000000003 RBP: 0000000002126a30 R08: 0000000000000018 R09: 0000000000168000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000002125030 R13: 0000000000000561 R14: 0000000002125080 R15: 0000000002126a48 Showing all locks held in the system: 3 locks held by kworker/u4:0/5: #0: ((wq_completion)"writeback"){+.+.}, at: [] __write_once_size include/linux/compiler.h:207 [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+0xad4/0x1bc0 kernel/workqueue.c:2083 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [] process_one_work+0xb2c/0x1bc0 kernel/workqueue.c:2087 #2: (&type->s_umount_key#31){++++}, at: [] trylock_super+0x20/0x100 fs/super.c:392 2 locks held by khungtaskd/655: #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 1 lock held by rsyslogd/2888: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x131/0x1a0 fs/file.c:768 2 locks held by getty/2971: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2972: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2973: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2974: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2975: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 2 locks held by getty/2976: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 1 lock held by blkid/7772: #0: (&bdev->bd_mutex){+.+.}, at: [] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1793 1 lock held by syz-executor0/8529: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by syz-executor0/8567: #0: (&bdev->bd_mutex){+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 2 locks held by getty/8621: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 655 Comm: khungtaskd Not tainted 4.14.0-rc7-next-20171103+ #38 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+0x20e/0x240 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+0x3c9/0x4b0 kernel/kthread.c:242 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc7-next-20171103+ #38 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffffffff85e2f380 task.stack: ffffffff85e00000 RIP: 0010:trace_softirqs_off+0x0/0x340 kernel/locking/lockdep.c:3010 RSP: 0018:ffff8801db207d28 EFLAGS: 00000046 RAX: 0000000080000201 RBX: 0000000000000086 RCX: 1ffff1003b6435f9 RDX: 1ffffffff0bd9672 RSI: 0000000080000001 RDI: ffffffff81425e57 RBP: ffff8801db207d48 R08: 1ffff1003b644cce R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff81425e57 R13: 1ffff1003b640fb1 R14: ffff8801db207e68 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffe5deddf8 CR3: 00000001d31f4000 CR4: 00000000001406f0 Call Trace: local_bh_disable include/linux/bottom_half.h:19 [inline] irq_enter+0xb8/0xe0 kernel/softirq.c:344 scheduler_ipi+0x23d/0x820 kernel/sched/core.c:1790 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:795 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff85e07d08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0bc0fa4 RCX: 0000000000000000 RDX: 1ffffffff0bd9674 RSI: 0000000000000001 RDI: ffffffff85ecb3a0 RBP: ffffffff85e07d08 R08: ffffffff85bb0aa0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff85e07dc0 R14: ffffffff865b6f60 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xbf/0x430 arch/x86/kernel/process.c:342 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:333 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:435 start_kernel+0x729/0x74f init/main.c:710 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 Code: 00 e9 6f fe ff ff e8 d0 ac 4f 00 e9 94 fe ff ff e8 66 ad 4f 00 e9 d2 fe ff ff e8 5c ad 4f 00 e9 a8 fd ff ff 0f 1f 80 00 00 00 00 <55> 48 b8 00 00 00 00 00 fc ff df 48 89 e5 41 55 49 89 fd 48 c7