Buffer I/O error on dev loop0, logical block 7, async page read
INFO: task kworker/u4:3:1339 blocked for more than 120 seconds.
      Not tainted 4.9.68-gfb66dc2 #107
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:3    D26880  1339      2 0x00000000
Workqueue: events_unbound flush_to_ldisc
 ffff8801d1413000 ffff8801a551af40 ffff8801c0e00a80 ffff8801d9b86000
 ffff8801db221418 ffff8801d14c7850 ffffffff8389920b ffff8801d14c7828
 ffffffff8123885f 00ffffff838a4b7a ffff8801db221ce8 ffff8801db221d10
Call Trace:
 [<ffffffff8389a7af>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a4c90>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3a18>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a3a12>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a3a12>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff82005e01>] n_tty_receive_buf_common+0x81/0x2110 drivers/tty/n_tty.c:1674
 [<ffffffff82007ec3>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
 [<ffffffff8200de07>] tty_ldisc_receive_buf+0xa7/0x180 drivers/tty/tty_buffer.c:455
 [<ffffffff8200edf3>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
 [<ffffffff8200edf3>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
 [<ffffffff811877cf>] process_one_work+0x78f/0x15f0 kernel/workqueue.c:2090
 [<ffffffff81188710>] worker_thread+0xe0/0x10d0 kernel/workqueue.c:2224
 [<ffffffff811985ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aac6a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff812355d0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
5 locks held by kworker/u4:3/1339:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] __write_once_size include/linux/compiler.h:272 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] atomic_long_set include/asm-generic/atomic-long.h:56 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] set_work_data kernel/workqueue.c:616 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff811876e9>] process_one_work+0x6a9/0x15f0 kernel/workqueue.c:2083
 #1:  ((&buf->work)){+.+...}, at: [<ffffffff8118771b>] process_one_work+0x6db/0x15f0 kernel/workqueue.c:2087
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff8200c09b>] tty_ldisc_ref+0x1b/0x80 drivers/tty/tty_ldisc.c:294
 #3:  (&port->buf.lock/1){+.+...}, at: [<ffffffff8200ec26>] flush_to_ldisc+0x86/0x370 drivers/tty/tty_buffer.c:505
 #4:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff82005e01>] n_tty_receive_buf_common+0x81/0x2110 drivers/tty/n_tty.c:1674
2 locks held by getty/3309:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8bd2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001ec4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor5/22149:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8bd2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001ec4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff82001ee7>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
2 locks held by syz-executor5/22159:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8bd2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff8200a655>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
2 locks held by syz-executor5/22172:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8bd2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff81fff129>] n_tty_ioctl+0x79/0x2d0 drivers/tty/n_tty.c:2429
2 locks held by syz-executor5/22191:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8bd2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff8200a655>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.68-gfb66dc2 #107
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d94efd00 ffffffff81d90889 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba1a0 ffff8801d94efd38
 ffffffff81d9b9ad 0000000000000001 0000000000000000 ffff8801d1413418
Call Trace:
 [<ffffffff81d90889>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90889>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9b9ad>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9bae7>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba294>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff813703d0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703d0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703d0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703d0>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aac6a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 22141 Comm: syz-executor5 Not tainted 4.9.68-gfb66dc2 #107
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d6423000 task.stack: ffff8801cef38000
RIP: 0010:[<ffffffff81368202>] 
c [<ffffffff81368202>] __sanitizer_cov_trace_pc+0x42/0x60 kernel/kcov.c:82
RSP: 0018:ffff8801cef3fb28  EFLAGS: 00000216
RAX: 0000000000010000 RBX: ffffc9000603d060 RCX: ffffc90003d5d000
RDX: 0000000000010000 RSI: 0000000014312a23 RDI: ffffc9000603e260
RBP: ffff8801cef3fb28 R08: 1ffff1003ac8471a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d6423000 R12: ffffc9000603c000
R13: 00000006fc829814 R14: 0000000020a27000 R15: ffff8801a596dfb8
FS:  00007f0c2fec0700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0ef6a62db8 CR3: 00000001c04e9000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801cef3fb78
c ffffffff81fff2bc
c ffffffffffffffff
c 0000000000000813
c
 0000000000000000
c ffff8801a596dd80
c 1ffff10039de7f75
c 000000000000541b
c
 ffffffffffffffe7
c ffff8801d59b0600
c ffff8801cef3fd70
c ffffffff81ff8033
c
Call Trace:
 [<ffffffff81fff2bc>] inq_canon drivers/tty/n_tty.c:2411 [inline]
 [<ffffffff81fff2bc>] n_tty_ioctl+0x20c/0x2d0 drivers/tty/n_tty.c:2431
 [<ffffffff81ff8033>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa71a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa71a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab73f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab73f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838aa9c5>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
cca 
c7e 
c81 
ce2 
c00 
c01 
c1f 
c00 
c75 
c0b 
c8b 
c90 
c68 
c12 
c00 
c00 
c83 
cfa 
c01 
c74 
c02 
c5d 
cc3 
c48 
c8b 
c88 
c70 
c12 
c00 
c00 
c8b 
c80 
c6c 
c12 
c00 
c00 
c48 
c8b 
c11 
c48 
c83 
cc2 
c01 
c<48> 
c39 
cd0 
c76 
ce5 
c48 
c8b 
c45 
c08 
c48 
c89 
c04 
cd1 
c48 
c89 
c11 
c5d 
cc3 
c66 
c90 
c66 
c