[    2.027582] ip (244) used greatest stack depth: 12832 bytes left
[    2.111598] ip (250) used greatest stack depth: 12336 bytes left
[    2.800748] ip (282) used greatest stack depth: 12200 bytes left
[  731.632722] blackhole_netdev_xmit(): Dropping skb.
[  731.632805] blackhole_netdev_xmit(): Dropping skb.
[  731.632888] blackhole_netdev_xmit(): Dropping skb.
[  731.632957] blackhole_netdev_xmit(): Dropping skb.