Buffer I/O error on dev loop0, logical block 0, async page read
INFO: task blkid:10687 blocked for more than 120 seconds.
      Not tainted 4.9.93-gf6bec4e #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid           D27864 10687  30215 0x00000006
 ffff8801a141c800 ffff8801c717c540 ffff8801b8f48540 ffff8801c71a0000
 ffff8801db221b98 ffff8801d8e97310 ffffffff838c4a7d 0000000041b58ab3
 ffffffff841a45f8 ffffffff81233c80 00ff8801d8e974e8 ffff8801db222468
Call Trace:
 [<ffffffff838c607f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3556
 [<ffffffff838d2491>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff838c425a>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5178
 [<ffffffff838c74c9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838c74c9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838c6d6e>] __wait_on_bit_lock+0xce/0x1c0 kernel/sched/wait.c:421
 [<ffffffff8143244f>] __lock_page+0xff/0x160 mm/filemap.c:934
 [<ffffffff814695e8>] lock_page include/linux/pagemap.h:454 [inline]
 [<ffffffff814695e8>] truncate_inode_pages_range+0x818/0x1290 mm/truncate.c:373
 [<ffffffff8146a084>] truncate_inode_pages+0x24/0x30 mm/truncate.c:401
 [<ffffffff8162bdfc>] kill_bdev+0xbc/0xf0 fs/block_dev.c:96
 [<ffffffff8162e143>] __blkdev_put+0x1e3/0x840 fs/block_dev.c:1586
 [<ffffffff8162f585>] blkdev_put+0x85/0x560 fs/block_dev.c:1663
 [<ffffffff8162faeb>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1670
 [<ffffffff81575a63>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff81575f85>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81195e2c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8113ea61>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113ea61>] do_exit+0x9e1/0x27c0 kernel/exit.c:837
 [<ffffffff81144b61>] do_group_exit+0x111/0x340 kernel/exit.c:941
 [<ffffffff811679df>] get_signal+0x4cf/0x1450 kernel/signal.c:2317
 [<ffffffff810524d7>] do_signal+0x87/0x19f0 arch/x86/kernel/signal.c:807
 [<ffffffff81005581>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:157
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff838d5953>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813643dc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813643dc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423b90>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3650:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d560c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3746:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838d3b22>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007e22>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
1 lock held by blkid/10687:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e01b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1579

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 515 Comm: khungtaskd Not tainted 4.9.93-gf6bec4e #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8cefd08 ffffffff81d9c299 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7d90 ffff8801d8cefd40
 ffffffff81da75d7 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9c299>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9c299>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da75d7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da756a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e94>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364974>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364974>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364974>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364974>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ab4d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d5b1c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3648 Comm: rs:main Q:Reg Not tainted 4.9.93-gf6bec4e #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c84eb000 task.stack: ffff8801c5408000
RIP: 0033:[<00007fbc5a927283>] 
c [<00007fbc5a927283>] 0x7fbc5a927283
RSP: 002b:00007fbc59552398  EFLAGS: 00000246
RAX: 00000000006d1d20 RBX: 00000000006b3fa0 RCX: 0000000000000000
RDX: 00000000006b3fa0 RSI: 0000000000000000 RDI: 00000000006d6f90
RBP: 00000000006b4140 R08: 00000000006d6f90 R09: 00000000006d1d00
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000006d6f90
R13: 0000000000000000 R14: 0000000000000003 R15: 00000000000000c0
FS:  00007fbc59553700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7faff5c000 CR3: 00000001cb342000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400