TITLE: INFO: task hung in copy_net_ns
TYPE: HANG

[  361.246294] INFO: task syz-executor0:6102 blocked for more than 120 seconds.
[  361.253503]       Not tainted 4.4.96+ #180
[  361.257716] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  361.265660] syz-executor0   D ffff8800b901f990     0  6102   1942 0x00000004
[  361.273110]  ffff8800b901f990 ffffffff835a8e78 ffff8800ac111780 0000000000000000
[  361.281099]  0000000000000000 ffff8801db61f5b8 ffff8801db61f5e0 ffff8801db61ec58
[  361.289101]  ffff8801db61ec40 ffffffff83218200 ffff8800ac111780 ffff8800b9018000
[  361.297131] Call Trace:
[  361.299714]  [<ffffffff829f5a8c>] schedule+0x9c/0x1b0
[  361.300009] unregister_netdevice: waiting for lo to become free. Usage count = 6
[  361.312401]  [<ffffffff829f6315>] schedule_preempt_disabled+0x15/0x20
[  361.318972]  [<ffffffff829fb0c0>] mutex_lock_nested+0x3b0/0x1130
[  361.325100]  [<ffffffff8223552c>] ? copy_net_ns+0xcc/0x220
[  361.330709]  [<ffffffff814cc088>] ? ___slab_alloc+0x458/0x550
[  361.336566]  [<ffffffff829fad10>] ? mutex_lock_killable_nested+0x1260/0x1260
[  361.343732]  [<ffffffff814cc1de>] ? __slab_alloc+0x5e/0x90
[  361.349328]  [<ffffffff822354cc>] ? copy_net_ns+0x6c/0x220
[  361.354932]  [<ffffffff81229c28>] ? rcu_read_lock_sched_held+0x108/0x120
[  361.361746]  [<ffffffff814cc4b8>] ? kmem_cache_alloc+0x2a8/0x320
[  361.367875]  [<ffffffff822354cc>] ? copy_net_ns+0x6c/0x220
[  361.373472]  [<ffffffff8223552c>] copy_net_ns+0xcc/0x220