EXT4-fs error (device sda1): ext4_has_uninit_itable:3043: comm syz-executor0: Inode table for bg 0 marked as needing zeroing
EXT4-fs (sda1): re-mounted. Opts: init_itable=0x0000000000000000,,errors=continue
INFO: task kworker/u4:7:5508 blocked for more than 140 seconds.
      Not tainted 4.9.116-g0137ea2 #18
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:7    D25368  5508      2 0x00000000
Workqueue: netns cleanup_net
 ffff8801d3a08000 0000000000000000 ffff8801c4c9ca80 ffffffff84629800
 ffff8801db221c18 ffff88019d217770 ffffffff839ead0d ffffffff85597a90
 ffff8801d3a08000 0000000000001c89 00ff8801d3a08958 ffff8801db2224e8
Call Trace:
 [<ffffffff839ec30f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f8721>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839ef4d3>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839ef4d3>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839ef4d3>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff839ef4d3>] wait_for_completion+0x203/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119dda6>] kthread_stop+0xa6/0x5d0 kernel/kthread.c:513
 [<ffffffff830f929e>] pg_net_exit+0x3de/0x6e0 net/core/pktgen.c:3923
 [<ffffffff8305adc0>] ops_exit_list.isra.6+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff8305dc91>] cleanup_net+0x321/0x630 net/core/net_namespace.c:473
 [<ffffffff8118d181>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df76>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d0ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fbddc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
1 lock held by kworker/dying/4:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by kworker/u4:0/6:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d0c8>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
1 lock held by kworker/dying/120:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136677c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136677c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425e07>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by kworker/dying/1837:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by rs:main Q:Reg/3673:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d835c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572e3e>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572e3e>] vfs_write+0x3ae/0x530 fs/read_write.c:556
2 locks held by getty/3771:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f9db2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82120212>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor0/3859:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/3864:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/3866:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/3868:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/3870:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by kworker/u4:6/4926:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8118d08e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&sub_info->work)){+.+.+.}, at: [<ffffffff8118d0c8>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
3 locks held by kworker/u4:7/5508:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d08e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d08e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d08e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118d0c8>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305daaf>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
1 lock held by syz-executor7/16569:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/17342:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18504:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18510:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18513:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18517:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18518:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/18520:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_0/18537:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_1/18538:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/18585:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/18596:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/18677:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/18610:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/18612:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/18622:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor6/18632:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor5/18641:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cb85c>] lo_ioctl+0x8c/0x1690 drivers/block/loop.c:1353
1 lock held by syz-executor3/18651:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/18653:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor3/18665:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by loop5/18655:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by blkid/18656:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cb85c>] lo_ioctl+0x8c/0x1690 drivers/block/loop.c:1353
1 lock held by syz-executor7/18659:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/18660:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/18666:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/18670:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/18679:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/18667:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/18671:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cb85c>] lo_ioctl+0x8c/0x1690 drivers/block/loop.c:1353
1 lock held by syz-executor0/18680:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cb85c>] lo_ioctl+0x8c/0x1690 drivers/block/loop.c:1353
1 lock held by syz-executor0/18681:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by blkid/18668:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/18669:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by blkid/18672:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/18673:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/18674:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor1/18676:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by loop0/18675:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by modprobe/18678:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2e18>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.116-g0137ea2 #18
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86bfd08 ffffffff81eb46a9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d86bfd40
 ffffffff81ebf9a7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb46a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb46a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf9a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf93a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366d14>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d14>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d14>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d14>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fbddc>] 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 0xffffffff839fa816