[    2.334503] ip (280) used greatest stack depth: 12360 bytes left
[    7.540850] ip (657) used greatest stack depth: 12344 bytes left
[   25.306970] ip (2512) used greatest stack depth: 12128 bytes left
[  849.032929] blackhole_netdev_xmit(): Dropping skb.
[  849.032988] blackhole_netdev_xmit(): Dropping skb.
[  849.033022] blackhole_netdev_xmit(): Dropping skb.
[  849.033053] blackhole_netdev_xmit(): Dropping skb.