BTRFS error (device loop4): superblock checksum mismatch
BTRFS error (device loop4): open_ctree failed
INFO: task kworker/u4:0:6 blocked for more than 120 seconds.
      Not tainted 4.9.96-g71fce1e #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:0    D25352     6      2 0x00000000
Workqueue: netns cleanup_net
 ffff8801d9a38000 ffff8801bdcdaa00 ffff8801bdcdaa00 ffff8801ccdd9800
 ffff8801db221b98 ffff8801d9a47958 ffffffff839e240d ffff8801d9a388c8
 ffffed003b347118 ffff8801d9a38000 00fffc0000000000 ffff8801db222468
Call Trace:
 [<ffffffff839e3a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839e4393>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839e8816>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839e8816>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff830b06a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff834800d0>] ipmr_rules_exit net/ipv4/ipmr.c:290 [inline]
 [<ffffffff834800d0>] ipmr_net_exit+0x80/0x120 net/ipv4/ipmr.c:2805
 [<ffffffff83054c80>] ops_exit_list.isra.6+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff83057b51>] cleanup_net+0x321/0x630 net/core/net_namespace.c:473
 [<ffffffff8118ae31>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118bc26>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f34dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
3 locks held by kworker/0:0/4:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad3e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad3e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad3e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff8118ad3e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((addr_chk_work).work){+.+...}, at: [<ffffffff8118ad78>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830b06a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
4 locks held by kworker/u4:0/6:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118ad78>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305796f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
 #3:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830b06a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by khungtaskd/518:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423ce0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3675:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d579c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3771:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f14b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211c792>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor5/14733:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff832de2c5>] do_ip_vs_set_ctl+0x645/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2402
2 locks held by syz-executor5/14805:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830b06a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff832de58d>] do_ip_vs_set_ctl+0x90d/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2397
1 lock held by syz-executor5/14806:
 #0:  (ipvs->sync_mutex){+.+.+.}, at: [<ffffffff832de2c5>] do_ip_vs_set_ctl+0x645/0xbd0 net/netfilter/ipvs/ip_vs_ctl.c:2402
1 lock held by ipvs-b:4:0/14737:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830b06a7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 1
CPU: 1 PID: 518 Comm: khungtaskd Not tainted 4.9.96-g71fce1e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d84d7d08 ffffffff81eb0b69 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d84d7d40
 ffffffff81ebbe97 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebbe97>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebbe2a>] 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
 [<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c84>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f34dc>] 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 skipped: idling at pc 0xffffffff839f1f16