unregister_netdevice: waiting for lo to become free. Usage count = 2
leaked reference.
 __netdev_tracker_alloc include/linux/netdevice.h:4043 [inline]
 netdev_hold include/linux/netdevice.h:4072 [inline]
 dst_init+0xee/0x440 net/core/dst.c:52
 dst_alloc+0x155/0x190 net/core/dst.c:92
 rt_dst_alloc net/ipv4/route.c:1627 [inline]
 ip_route_input_slow net/ipv4/route.c:2367 [inline]
 ip_route_input_rcu+0x24da/0x3960 net/ipv4/route.c:2481
 ip_route_input_noref+0x16c/0x260 net/ipv4/route.c:2492
 ip_rcv_finish_core+0x57b/0x1b40 net/ipv4/ip_input.c:365
 ip_rcv_finish+0x146/0x260 net/ipv4/ip_input.c:447
 NF_HOOK+0x39d/0x450 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5538 [inline]
 __netif_receive_skb+0x1c6/0x530 net/core/dev.c:5652
 netif_receive_skb_internal net/core/dev.c:5738 [inline]
 netif_receive_skb+0x1f4/0x890 net/core/dev.c:5797
 tun_rx_batched+0x1b3/0x8e0 drivers/net/tun.c:1548
 tun_get_user+0x2c03/0x42d0 drivers/net/tun.c:1998
 tun_chr_write_iter+0x10c/0x1f0 drivers/net/tun.c:2044
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x857/0xbc0 fs/read_write.c:584
 ksys_write+0x19c/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2