INFO: task kworker/0:3:19876 blocked for more than 140 seconds.
      Not tainted 4.9.168+ #40
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:3     D29256 19876      2 0x80000000
Workqueue: ipv6_addrconf addrconf_verify_work
 ffff8801c7aa4740 ffff8801a2b31080 ffff8801db621000 ffff8801a5044740
 ffff8801db621018 ffff8801ce6a7a88 ffffffff8280028e ffff8801c7aa4740
 ffff8801ce6a7b60 0000000000000046 ffff8801db6218f0 1ffff10039cd4f40
Call Trace:
 [<000000000ce9b3a6>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000f637195e>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<00000000eba3eeea>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<00000000eba3eeea>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<000000003e690e9e>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<00000000983f391c>] addrconf_verify_work+0xe/0x20 net/ipv6/addrconf.c:4365
 [<00000000f2e0e5d0>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<00000000467a69b4>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<00000000927d0987>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000018abee0e>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<000000007587347e>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<000000007587347e>] watchdog+0x13c/0xae0 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<0000000095a5610c>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
2 locks held by getty/2026:
 #0:  (&tty->ldisc_sem){++++++}, at: [<000000003020faeb>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<000000001db24998>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
3 locks held by kworker/0:3/19876:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<00000000e63abdcf>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  ((addr_chk_work).work){+.+...}, at: [<00000000b4594d44>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (rtnl_mutex){+.+.+.}, at: [<000000003e690e9e>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
3 locks held by kworker/1:3/1960:
 #0:  ("events"){.+.+.+}, at: [<00000000e63abdcf>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  ((linkwatch_work).work){+.+...}, at: [<00000000b4594d44>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (rtnl_mutex){+.+.+.}, at: [<000000003e690e9e>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.168+ #40
 ffff8801d98d7cc8 ffffffff81b4f5d1 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5a86c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<00000000a277657d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000a277657d>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000000d79eb00>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<000000009b9a1fd1>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<0000000057cfa446>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<0000000097f7f855>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<0000000097f7f855>] check_hung_task kernel/hung_task.c:125 [inline]
 [<0000000097f7f855>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<0000000097f7f855>] watchdog+0x661/0xae0 kernel/hung_task.c:239
 [<00000000927d0987>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000018abee0e>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 30801 Comm: syz-executor.5 Not tainted 4.9.168+ #40
task: 00000000c6a2cd94 task.stack: 00000000ee582fe0
RIP: 0033:[<0000000000401584>] 
c [<00000000a63c177b>] 0x401584
RSP: 002b:00007f809d886690  EFLAGS: 00000282
RAX: 000000008511963d RBX: 000000000000000b RCX: 0000000000458c29
RDX: 0000000000000001 RSI: 00007f809d8866c0 RDI: 000000000000000b
RBP: 0000000000000000 R08: 0000000020000040 R09: 0000000000000000
R10: 000000000000000c R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000458 R15: 0000000020000180
FS:  00007f809d887700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000e2e3e0 CR3: 00000001c7469000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600