unregister_netdevice: waiting for lo to become free. Usage count = 2
leaked reference.
 __netdev_tracker_alloc include/linux/netdevice.h:4051 [inline]
 netdev_hold include/linux/netdevice.h:4080 [inline]
 dst_init+0xda/0x410 net/core/dst.c:52
 dst_alloc+0x12a/0x160 net/core/dst.c:92
 rt_dst_alloc net/ipv4/route.c:1662 [inline]
 ip_route_input_slow net/ipv4/route.c:2402 [inline]
 ip_route_input_rcu+0x2055/0x3160 net/ipv4/route.c:2516
 ip_route_input_noref+0x180/0x270 net/ipv4/route.c:2527
 ip_rcv_finish_core+0x5a6/0x1bd0 net/ipv4/ip_input.c:365
 ip_rcv_finish+0x14a/0x250 net/ipv4/ip_input.c:447
 NF_HOOK+0x329/0x3b0 include/linux/netfilter.h:302
 __netif_receive_skb_one_core net/core/dev.c:5581 [inline]
 __netif_receive_skb+0xcc/0x290 net/core/dev.c:5695
 netif_receive_skb_internal net/core/dev.c:5781 [inline]
 netif_receive_skb+0x1d4/0x830 net/core/dev.c:5840
 tun_rx_batched+0x1db/0x790 drivers/net/tun.c:1548
 tun_get_user+0x286f/0x3c70 drivers/net/tun.c:1998
 tun_chr_write_iter+0x112/0x1f0 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+0x4b1/0xa30 fs/read_write.c:584
 ksys_write+0x14c/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2