unregister_netdevice: waiting for batadv_slave_0 to become free. Usage count = 2
ref_tracker: netdev@ffff88807e64c610 has 1/1 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4349 [inline]
     netdev_tracker_alloc include/linux/netdevice.h:4361 [inline]
     netdev_get_by_index+0x79/0xb0 net/core/dev.c:1008
     fib6_nh_init+0x1cd/0x1ff0 net/ipv6/route.c:3592
     nh_create_ipv6 net/ipv4/nexthop.c:2862 [inline]
     nexthop_create net/ipv4/nexthop.c:2913 [inline]
     nexthop_add net/ipv4/nexthop.c:2950 [inline]
     rtm_new_nexthop+0x38d6/0x7eb0 net/ipv4/nexthop.c:3264
     rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6946
     netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
     netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
     netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346
     netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
     sock_sendmsg_nosec net/socket.c:714 [inline]
     __sock_sendmsg+0x21c/0x270 net/socket.c:729
     ____sys_sendmsg+0x505/0x830 net/socket.c:2614
     ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
     __sys_sendmsg net/socket.c:2700 [inline]
     __do_sys_sendmsg net/socket.c:2705 [inline]
     __se_sys_sendmsg net/socket.c:2703 [inline]
     __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703
     do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
     do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
     entry_SYSCALL_64_after_hwframe+0x77/0x7f