ip6_tunnel: l0 xmit: Local address not yet configured!
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
ip6_tunnel: ip6tnl2 xmit: Local address not yet configured!
INFO: task kworker/u4:30:6817 blocked for more than 140 seconds.
      Not tainted 4.9.182+ #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:30   D26616  6817      2 0x80000000
Workqueue: netns cleanup_net
 0000000000000083 ffff8801a2a20000 0000000000000000 ffff8801db621000
 ffff8801d6fd2f80 ffff8801db621018 ffff8801a211f640 ffffffff8280a19e
 ffff8801a211f590 ffffffff8120b6c5 0000000000000292 ffff8801db6218f0
Call Trace:
 [<000000007fa253cc>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000ebf3fffc>] exp_funnel_lock kernel/rcu/tree_exp.h:279 [inline]
 [<00000000ebf3fffc>] _synchronize_rcu_expedited+0x68a/0x850 kernel/rcu/tree_exp.h:569
 [<000000008c1cd710>] synchronize_rcu_expedited kernel/rcu/tree_exp.h:687 [inline]
 [<000000008c1cd710>] synchronize_rcu_expedited+0x22/0x30 kernel/rcu/tree_exp.h:681
 [<00000000a7bf4bb7>] synchronize_net+0x2f/0x50 net/core/dev.c:7862
 [<000000009d82eb6d>] rollback_registered_many+0x80f/0xb50 net/core/dev.c:6890
 [<00000000af0c72de>] unregister_netdevice_many.part.0+0x1b/0x1e0 net/core/dev.c:7907
 [<0000000088311aad>] unregister_netdevice_many+0x3b/0x50 net/core/dev.c:7906
 [<00000000a2cc1ad6>] ip6_tnl_destroy_tunnels net/ipv6/ip6_tunnel.c:2193 [inline]
 [<00000000a2cc1ad6>] ip6_tnl_exit_net+0x3e8/0x5b0 net/ipv6/ip6_tunnel.c:2240
 [<000000001e7cc857>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<00000000f6105267>] cleanup_net+0x3d6/0x8a0 net/core/net_namespace.c:474
 [<00000000739afb27>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<000000000dd266ad>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<00000000e1f9ec42>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000e0c90647>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<00000000ced5d102>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000ced5d102>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<00000000b6515e59>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/1905:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<000000005aafaa6e>] __fdget_pos+0xa8/0xd0 fs/file.c:782
2 locks held by getty/2032:
 #0:  (&tty->ldisc_sem){++++++}, at: [<000000002e667a3d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<0000000059360690>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
4 locks held by kworker/u4:30/6817:
 #0:  ("%s""netns"){.+.+.+}, at: [<000000004eba7a84>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  (net_cleanup_work){+.+.+.}, at: [<00000000a4f8d10d>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (net_mutex){+.+.+.}, at: [<00000000d62354d4>] cleanup_net+0x131/0x8a0 net/core/net_namespace.c:440
 #3:  (rtnl_mutex){+.+.+.}, at: [<00000000bea5ff50>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
3 locks held by kworker/0:3/8925:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<000000004eba7a84>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107
 #1:  ((addr_chk_work).work){+.+...}, at: [<00000000a4f8d10d>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111
 #2:  (rtnl_mutex){+.+.+.}, at: [<00000000bea5ff50>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.2/10621:
 #0:  (rtnl_mutex){+.+.+.}, at: [<00000000bea5ff50>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.182+ #2
 ffff8801d98d7cc8 ffffffff81b57e21 0000000000000001 0000000000000000
 0000000000000001 ffffffff81099901 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b630bc 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<000000008935fdd9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000008935fdd9>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000ff670df8>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000b147c0b0>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<0000000010113211>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<0000000005d234e1>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<0000000005d234e1>] check_hung_task kernel/hung_task.c:126 [inline]
 [<0000000005d234e1>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<0000000005d234e1>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<00000000e1f9ec42>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000e0c90647>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff828192f1