IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
INFO: task kworker/u4:6:5116 blocked for more than 120 seconds.
      Not tainted 4.9.110-g00a0bcb #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:6    D25944  5116      2 0x00000000
Workqueue: events_unbound flush_to_ldisc
 ffff88019cfe3000 ffff8801d4a464c0 ffff8801c94dc540 ffff88019e8d3000
 ffff8801db321c18 ffff88019cdf78c8 ffffffff839e6ded ffff88019cfe38c8
 ffffed00339fc718 ffff88019cfe3000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839e83ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839e8d73>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839ed1f6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839ed1f6>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff8211b9b0>] commit_echoes+0x120/0x1b0 drivers/tty/n_tty.c:764
 [<ffffffff8212349a>] n_tty_receive_char_inline drivers/tty/n_tty.c:1390 [inline]
 [<ffffffff8212349a>] n_tty_receive_buf_standard drivers/tty/n_tty.c:1552 [inline]
 [<ffffffff8212349a>] __receive_buf drivers/tty/n_tty.c:1615 [inline]
 [<ffffffff8212349a>] n_tty_receive_buf_common+0x70a/0x2300 drivers/tty/n_tty.c:1711
 [<ffffffff821250c3>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
 [<ffffffff8212abbf>] tty_ldisc_receive_buf+0xaf/0x190 drivers/tty/tty_buffer.c:455
 [<ffffffff8212bbc3>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
 [<ffffffff8212bbc3>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
 [<ffffffff8118d121>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df16>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3768:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f5e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211e1e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
6 locks held by kworker/u4:6/5116:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&buf->work)){+.+...}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82129390>] tty_ldisc_ref+0x20/0x80 drivers/tty/tty_ldisc.c:296
 #3:  (&port->buf.lock/1){+.+...}, at: [<ffffffff8212b9f6>] flush_to_ldisc+0x86/0x370 drivers/tty/tty_buffer.c:505
 #4:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff82122e1b>] n_tty_receive_buf_common+0x8b/0x2300 drivers/tty/n_tty.c:1674
 #5:  (&ldata->output_lock){+.+...}, at: [<ffffffff8211b9b0>] commit_echoes+0x120/0x1b0 drivers/tty/n_tty.c:764

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.110-g00a0bcb #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9007d08 ffffffff81eb2329 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9580 ffff8801d9007d40
 ffffffff81ebd627 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb2329>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2329>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebd627>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd5ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] 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: 28315 Comm: syz-executor6 Not tainted 4.9.110-g00a0bcb #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88019d084800 task.stack: ffff8801a9998000
RIP: 0010:[<ffffffff8211a0c5>] 
c [<ffffffff8211a0c5>] __process_echoes+0x605/0x780 drivers/tty/n_tty.c:734
RSP: 0018:ffff8801a999f8a8  EFLAGS: 00000246
RAX: 0000000000000f76 RBX: ffffc900073fb000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8211a08f RDI: ffffc900073fd1d6
RBP: ffff8801a999f910 R08: ffff88019d085138 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000009cebf9f76
R13: 0000000000005308 R14: dffffc0000000000 R15: 00000009cebf9f76
FS:  00007f6c05ec6700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f658147c000 CR3: 00000001ca1a2000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff8801a999f8a0
c ffff88019d0850b4
c ffffc900073fd278
c ffffed0034224d35
c
 ffff8801a11269ac
c ffffc900073fb020
c 0000000000000000
c ffff8801a1126600
c
 ffffc900073fb000
c ffff8801a1126600
c 0000000000005308
c ffffc900073fd300
c
Call Trace:
 [<ffffffff8211b9d7>] commit_echoes+0x147/0x1b0 drivers/tty/n_tty.c:766
 [<ffffffff82120c34>] n_tty_receive_char_special+0xd64/0x2860 drivers/tty/n_tty.c:1286
 [<ffffffff82123603>] n_tty_receive_buf_standard drivers/tty/n_tty.c:1553 [inline]
 [<ffffffff82123603>] __receive_buf drivers/tty/n_tty.c:1615 [inline]
 [<ffffffff82123603>] n_tty_receive_buf_common+0x873/0x2300 drivers/tty/n_tty.c:1711
 [<ffffffff82125100>] n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1740
 [<ffffffff8211551f>] tiocsti drivers/tty/tty_io.c:2314 [inline]
 [<ffffffff8211551f>] tty_ioctl+0xc8f/0x2270 drivers/tty/tty_io.c:2905
 [<ffffffff815b2b9c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b2b9c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b2b9c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b3c1f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b3c1f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f7cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c03 
c60 
c12 
c00 
c00 
c48 
c89 
cfa 
c48 
c89 
cf9 
c48 
cc1 
cea 
c03 
c83 
ce1 
c07 
c42 
c0f 
cb6 
c14 
c32 
c38 
cca 
c7f 
c08 
c84 
cd2 
c0f 
c85 
cb0 
c00 
c00 
c00 
c80 
cbc 
c03 
c60 
c12 
c00 
c00 
cff 
c<4d> 
c8d 
c7c 
c24 
c01 
c75 
ca4 
ce8 
c6f 
c48 
c24 
cff 
c41 
c81 
ce7 
cff 
c0f 
c00 
c00 
c4a 
c8d 
c