INFO: task kworker/u4:3:1342 blocked for more than 120 seconds.
      Not tainted 4.9.69-g3f1d77c #108
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:3    D25536  1342      2 0x00000000
Workqueue: events_unbound flush_to_ldisc
 ffff8801d141b000 ffff8801cf1cdf80 ffff8801cf1cdf80 ffff8801d83a3000
 ffff8801db321418 ffff8801d14df850 ffffffff8389932b ffff8801d14df828
 ffffffff8123886f 00ffffff838a4c9a ffff8801db321ce8 ffff8801db321d10
Call Trace:
 [<ffffffff8389a8cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a4db0>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3bb8>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a3b32>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a3b32>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff82005fc1>] n_tty_receive_buf_common+0x81/0x2110 drivers/tty/n_tty.c:1674
 [<ffffffff82008083>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
 [<ffffffff8200dfc7>] tty_ldisc_receive_buf+0xa7/0x180 drivers/tty/tty_buffer.c:455
 [<ffffffff8200efb3>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
 [<ffffffff8200efb3>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
 [<ffffffff8118780f>] process_one_work+0x78f/0x15f0 kernel/workqueue.c:2091
 [<ffffffff81188750>] worker_thread+0xe0/0x10d0 kernel/workqueue.c:2225
 [<ffffffff811985ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aadaa>] 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: [<ffffffff8136fe15>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe15>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff812355e0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
5 locks held by kworker/u4:3/1342:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] __write_once_size include/linux/compiler.h:272 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] atomic_long_set include/asm-generic/atomic-long.h:56 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] set_work_data kernel/workqueue.c:616 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff81187729>] process_one_work+0x6a9/0x15f0 kernel/workqueue.c:2084
 #1:  ((&buf->work)){+.+...}, at: [<ffffffff8118775b>] process_one_work+0x6db/0x15f0 kernel/workqueue.c:2088
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff8200c25b>] tty_ldisc_ref+0x1b/0x80 drivers/tty/tty_ldisc.c:294
 #3:  (&port->buf.lock/1){+.+...}, at: [<ffffffff8200ede6>] flush_to_ldisc+0x86/0x370 drivers/tty/tty_buffer.c:505
 #4:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff82005fc1>] n_tty_receive_buf_common+0x81/0x2110 drivers/tty/n_tty.c:1674
2 locks held by getty/3307:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82002084>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor5/7324:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82002084>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff820020a7>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
2 locks held by syz-executor5/7330:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8200a815>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
2 locks held by syz-executor5/7339:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8200a815>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
2 locks held by syz-executor5/7346:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8200a815>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
2 locks held by syz-executor5/7347:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff81fff2e9>] n_tty_ioctl+0x79/0x2d0 drivers/tty/n_tty.c:2429
2 locks held by syz-executor5/7359:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8cf2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8200a815>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.69-g3f1d77c #108
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9b5fd00 ffffffff81d90a29 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba1a0 ffff8801d9b5fd38
 ffffffff81d9bb4d 0000000000000001 0000000000000000 ffff8801d141b418
Call Trace:
 [<ffffffff81d90a29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90a29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9bb4d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9bc87>] 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
 [<ffffffff813703e0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703e0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703e0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703e0>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aadaa>] 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: 7319 Comm: syz-executor5 Not tainted 4.9.69-g3f1d77c #108
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d83a3000 task.stack: ffff8801c59a8000
RIP: 0010:[<ffffffff813681d0>] 
c [<ffffffff813681d0>] __sanitizer_cov_trace_pc+0x0/0x60
RSP: 0018:ffff8801c59afb30  EFLAGS: 00000293
RAX: 0000000000010000 RBX: ffffc9000558e060 RCX: ffffc90003761000
RDX: 0000000000010000 RSI: 00000000ea784573 RDI: ffffc9000558f260
RBP: ffff8801c59afb78 R08: 1ffff1003b07471a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d83a3000 R12: ffffc9000558d000
R13: 0000000532439111 R14: 0000000020fe6000 R15: ffff8801d0fad738
FS:  00007f85d1972700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001228d58 CR3: 00000001c4843000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81fff47c
c ffffffffffffffff
c 0000000000000110
c 0000000000000000
c
 ffff8801d0fad500
c 1ffff10038b35f75
c 000000000000541b
c ffffffffffffffe7
c
 ffff8801a988b800
c ffff8801c59afd70
c ffffffff81ff81f3
c ffff8801d83a3000
c
Call Trace:
 [<ffffffff81ff81f3>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa7da>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa7da>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab7ff>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab7ff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838aab05>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
c1d 
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c89 
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c29 
c1d 
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cff 
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cff 
c48 
c89 
cdf 
ce8 
cd2 
c28 
c1d 
c00 
ce9 
c29 
cff 
cff 
cff 
c66 
c2e 
c0f 
c1f 
c84 
c00 
c00 
c00 
c00 
c00 
c0f 
c1f 
c00 
c<55> 
c65 
c48 
c8b 
c04 
c25 
c40 
c55 
c01 
c00 
c48 
c85 
cc0 
c48 
c89 
ce5 
c74 
c1a 
c65 
c8b 
c15 
c