unregister_netdevice: waiting for lo to become free. Usage count = 8
ref_tracker: netdev@ffff888117340610 has 6/7 users at
     dst_init+0xd9/0x450
     dst_alloc+0x12a/0x170
     rt_dst_clone+0x52/0x680
     ip_mc_finish_output+0xec/0x250
     ip_mc_output+0x3a3/0x590
     __ip_queue_xmit+0x1106/0x1b00
     __tcp_transmit_skb+0x2215/0x3680
     tcp_send_probe0+0x51/0x580
     tcp_write_timer+0x162/0x2e0
     call_timer_fn+0x17e/0x5f0
     __run_timer_base+0x61a/0x860
     run_timer_softirq+0xb7/0x180
     handle_softirqs+0x286/0x870
     __irq_exit_rcu+0xca/0x1f0
     irq_exit_rcu+0x9/0x30
     sysvec_apic_timer_interrupt+0xa6/0xc0

ref_tracker: netdev@ffff888117340610 has 1/7 users at
     dst_init+0xd9/0x450
     dst_alloc+0x12a/0x170
     rt_dst_clone+0x52/0x680
     ip_mc_finish_output+0xec/0x250
     ip_mc_output+0x3a3/0x590
     __ip_queue_xmit+0x1106/0x1b00
     __tcp_transmit_skb+0x2215/0x3680
     do_tcp_setsockopt+0x187e/0x1f10
     do_sock_setsockopt+0x17c/0x1b0
     __x64_sys_setsockopt+0x13f/0x1b0
     do_syscall_64+0xfa/0x3b0
     entry_SYSCALL_64_after_hwframe+0x77/0x7f

