INFO: task kworker/u4:1:22 blocked for more than 120 seconds.
      Not tainted 4.9.94-g8683408 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:1    D25736    22      2 0x00000000
Workqueue: netns cleanup_net
 ffff8801d9bf1800 ffff8801aa4faa00 ffff88019bacd500 ffff880190863000
 ffff8801db221b98 ffff8801d94f7958 ffffffff838c040d ffff8801d9bf20c8
 ffffed003b37e418 ffff8801d9bf1800 00fffc0000000000 ffff8801db222468
Call Trace:
 [<ffffffff838c1a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff838c2393>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff838c6816>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff838c6816>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff8335e0d0>] ipmr_rules_exit net/ipv4/ipmr.c:290 [inline]
 [<ffffffff8335e0d0>] ipmr_net_exit+0x80/0x120 net/ipv4/ipmr.c:2805
 [<ffffffff82f32c80>] ops_exit_list.isra.6+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff82f35b51>] cleanup_net+0x321/0x630 net/core/net_namespace.c:473
 [<ffffffff8118ae01>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118bbf6>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d14dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
4 locks held by kworker/u4:1/22:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad0e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad0e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad0e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad0e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118ad48>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff82f3596f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
 #3:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
3 locks held by kworker/0:1/25:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad0e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((addr_chk_work).work){+.+...}, at: [<ffffffff8118ad48>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by khungtaskd/516:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423bb0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3646:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d565c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3742:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838cf4b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007082>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor2/14130:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff831bc2c5>] do_ip_vs_set_ctl+0x645/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2402
2 locks held by syz-executor2/14141:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff831bc58d>] do_ip_vs_set_ctl+0x90d/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2397
1 lock held by syz-executor4/14133:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor4/14188:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor4/14193:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by ipvs-b:8:0/14142:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor1/14150:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f931cb>] rtnl_lock net/core/rtnetlink.c:70 [inline]
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f931cb>] rtnetlink_rcv+0x1b/0x40 net/core/rtnetlink.c:4064
1 lock held by syz-executor1/14189:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f931cb>] rtnl_lock net/core/rtnetlink.c:70 [inline]
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f931cb>] rtnetlink_rcv+0x1b/0x40 net/core/rtnetlink.c:4064
1 lock held by syz-executor3/14169:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff82f8e6a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 0
CPU: 0 PID: 516 Comm: khungtaskd Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86bfd08 ffffffff81d9b509 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7d60 ffff8801d86bfd40
 ffffffff81da6837 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9b509>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9b509>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da6837>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da67ca>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e64>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d14dc>] 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: 0 Comm: swapper/1 Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9b73000 task.stack: ffff8801d9b88000
RIP: 0010:[<ffffffff8122ddcb>] 
c [<ffffffff8122ddcb>] match_held_lock+0x1b/0x570 kernel/locking/lockdep.c:3405
RSP: 0018:ffff8801db307d30  EFLAGS: 00000086
RAX: dffffc0000000000 RBX: ffff8801d9b73000 RCX: 1ffffffff084247d
RDX: 1ffff1003b36e718 RSI: ffffffff844bbf80 RDI: ffff8801d9b738d8
RBP: ffff8801db307d48 R08: ffff8801d9b738e8 R09: 0000000000000001
R10: ffff8801d9b73000 R11: 0000000000000001 R12: ffffed003b36e718
R13: ffff8801d9b738c8 R14: ffffffff844bbf80 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000024b8b10 CR3: 00000001be9c8000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d9b738c8
c ffffffff844bbf80
c 0000000000000000
c ffff8801db307d88
c
 ffffffff8122e3c2
c ffff8801d9b738c0
c 0000000000000246
c ffff8801d9b73000
c
 ffffffff844bbf80
c ffff8801db321b80
c 000000010000f1ad
c ffff8801db307db0
c
Call Trace:
 <IRQ> 
d [<ffffffff8122e3c2>] __lock_is_held+0xa2/0xf0 kernel/locking/lockdep.c:3597
 [<ffffffff8122ebf4>] lock_is_held+0xb4/0x140 kernel/locking/lockdep.c:3794
 [<ffffffff81205fa3>] rebalance_domains+0x803/0xbc0 kernel/sched/fair.c:10078
 [<ffffffff81206659>] run_rebalance_domains+0x2f9/0x510 kernel/sched/fair.c:10332
 [<ffffffff838d7efb>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff81149037>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81149037>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff838d5aa1>] smp_reschedule_interrupt+0x71/0x90 arch/x86/kernel/smp.c:270
 [<ffffffff838d3610>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff838cff16>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838cf555>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff838cf555>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff81069fa0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:286
 [<ffffffff838d0375>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81220e35>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81220e35>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81220e35>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff810ad1f3>] start_secondary+0x323/0x400 arch/x86/kernel/smpboot.c:254
Code: 
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c<48> 
c89 
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c51 
c