INFO: task kworker/u4:10:21867 blocked for more than 120 seconds.
      Not tainted 4.9.108-gb7d377b #47
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:10   D25368 21867      2 0x00000000
Workqueue: netns cleanup_net
 ffff8801cc573000 ffff8801cb3dea00 ffff8801b7e64000 ffff8801cd664800
 ffff8801db321c18 ffff880189b07770 ffffffff839e8aed ffffffff85597ad0
 ffffffff846c9760 0000000000000771 00ff8801cc573958 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea0ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f6501>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839ed2b3>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839ed2b3>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839ed2b3>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff839ed2b3>] wait_for_completion+0x203/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119dd46>] kthread_stop+0xa6/0x5d0 kernel/kthread.c:513
 [<ffffffff830f828e>] pg_net_exit+0x3de/0x6e0 net/core/pktgen.c:3923
 [<ffffffff83059d50>] ops_exit_list.isra.6+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff8305cc21>] cleanup_net+0x321/0x630 net/core/net_namespace.c:473
 [<ffffffff8118d121>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df16>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by kworker/u4:0/6:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by kworker/u4:1/22:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by kworker/u4:2/67:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3676:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d803c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3773:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor1/3827:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/8603:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/13982:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/20536:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
3 locks held by kworker/u4:10/21867:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305ca3f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
1 lock held by syz-executor4/23777:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/26737:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by kworker/u4:7/1607:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by kworker/u4:11/1615:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by kworker/u4:13/1623:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
1 lock held by syz-executor0/4164:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/4168:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6442:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6443:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6444:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6445:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6447:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/6449:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_0/6573:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_1/6574:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/6635:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/6661:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/6666:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/6625:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/6634:
 #0:  (net_mutex){+.+.+.}, at: [<ffffffff8305d085>] copy_net_ns+0x155/0x290 net/core/net_namespace.c:406
1 lock held by syz-executor7/6662:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/6670:
 #0:  (net_mutex){+.+.+.}, at: [<ffffffff8305d085>] copy_net_ns+0x155/0x290 net/core/net_namespace.c:406
1 lock held by syz-executor7/6672:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/6629:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/6633:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/6660:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/6630:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/6637:
 #0:  (net_mutex){+.+.+.}, at: [<ffffffff8305d085>] copy_net_ns+0x155/0x290 net/core/net_namespace.c:406
1 lock held by syz-executor1/6663:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/6665:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6647:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6650:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6674:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6675:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6677:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/6678:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/6651:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/6653:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/6676:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/6679:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/6681:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/6654:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/6655:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor4/6668:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/6669:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/6671:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/6656:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/6658:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/6659:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/6684:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/6685:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/6664:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by loop4/6667:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by blkid/6673:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by modprobe/6680:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/6682:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/6683:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/6686:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8547d08 ffffffff81eb3e29 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b96a0 ffff8801d8547d40
 ffffffff81ebf127 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] 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 skipped: idling at pc 0xffffffff839f85f6