unregister_netdevice: waiting for lo to become free. Usage count = 2 leaked reference. __netdev_tracker_alloc include/linux/netdevice.h:4020 [inline] netdev_hold include/linux/netdevice.h:4049 [inline] ipv6_add_dev+0x3e6/0x1190 net/ipv6/addrconf.c:401 addrconf_notify+0x64d/0xfb0 net/ipv6/addrconf.c:3552 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd4/0x170 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:1944 [inline] call_netdevice_notifiers_extack net/core/dev.c:1982 [inline] call_netdevice_notifiers+0x149/0x1c0 net/core/dev.c:1996 register_netdevice+0x1349/0x1790 net/core/dev.c:10078 register_netdev+0x3b/0x50 net/core/dev.c:10173 loopback_net_init+0x73/0x150 drivers/net/loopback.c:219 ops_init+0x341/0x5d0 net/core/net_namespace.c:135 setup_net+0x619/0xd40 net/core/net_namespace.c:333 copy_net_ns+0x353/0x590 net/core/net_namespace.c:483 create_new_namespaces+0x425/0x7a0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x11d/0x170 kernel/nsproxy.c:228 ksys_unshare+0x584/0xb20 kernel/fork.c:3202 __do_sys_unshare kernel/fork.c:3273 [inline] __se_sys_unshare kernel/fork.c:3271 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3271 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd