INFO: task kworker/u8:4:7780 blocked for more than 142 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:4    state:D stack:22960 pid:7780  tgid:7780  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 addrconf_verify_work+0x19/0x30
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u9:0/26:
3 locks held by kworker/u9:1/32:
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
3 locks held by kworker/u9:2/89:
3 locks held by kworker/0:2/794:
 #0: ffff88801a480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000452fbc0 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
