unregister_netdevice: waiting for lo to become free. Usage count = 2
leaked reference.
 ipv6_add_dev+0x345/0xec0
 addrconf_notify+0x47c/0xce0
 raw_notifier_call_chain+0xc8/0x100
 call_netdevice_notifiers+0x107/0x160
 register_netdevice+0x1213/0x15e0
 register_netdev+0x20/0x30
 loopback_net_init+0x6e/0x110
 ops_init+0x195/0x4c0
 setup_net+0x64d/0xd70
 copy_net_ns+0x29f/0x4a0
 create_new_namespaces+0x381/0x650
 unshare_nsproxy_namespaces+0xd6/0x110
 ksys_unshare+0x3db/0x820
 __x64_sys_unshare+0x33/0x40
 do_syscall_64+0x41/0xc0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd