unregister_netdevice: waiting for lo to become free. Usage count = 2 leaked reference. __netdev_tracker_alloc include/linux/netdevice.h:4038 [inline] netdev_hold include/linux/netdevice.h:4067 [inline] ipv6_add_dev+0x43e/0x13b0 net/ipv6/addrconf.c:401 addrconf_notify+0x63d/0x19f0 net/ipv6/addrconf.c:3552 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline] call_netdevice_notifiers net/core/dev.c:1997 [inline] register_netdevice+0xfb4/0x1640 net/core/dev.c:10084 register_netdev+0x31/0x50 net/core/dev.c:10179 loopback_net_init+0x7a/0x170 drivers/net/loopback.c:219 ops_init+0xb9/0x6b0 net/core/net_namespace.c:135 setup_net+0x793/0xe60 net/core/net_namespace.c:333 copy_net_ns+0x320/0x6b0 net/core/net_namespace.c:483 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:228 ksys_unshare+0x449/0x920 kernel/fork.c:3205 __do_sys_unshare kernel/fork.c:3276 [inline] __se_sys_unshare kernel/fork.c:3274 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3274 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd