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_clone+0x54/0x6b0 net/ipv4/route.c:1686
 ip_mc_finish_output+0x106/0x520 net/ipv4/ip_output.c:348
 NF_HOOK include/linux/netfilter.h:302 [inline]
 ip_mc_output+0x2a1/0x5e0 net/ipv4/ip_output.c:394
 dst_output include/net/dst.h:453 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 ip_send_skb+0x129/0x1c0 net/ipv4/ip_output.c:1600
 raw_sendmsg+0x1435/0x1930 net/ipv4/raw.c:653
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x59b/0x970 net/socket.c:2519
 ___sys_sendmsg+0x21c/0x290 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x19e/0x270 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2