[    2.157685] ip (275) used greatest stack depth: 12320 bytes left
[    9.745522] ip (1071) used greatest stack depth: 12272 bytes left
[   16.213024] ip (2147) used greatest stack depth: 12160 bytes left
[  705.841890] blackhole_netdev_xmit(): Dropping skb.
[  705.841951] blackhole_netdev_xmit(): Dropping skb.
[  705.841986] blackhole_netdev_xmit(): Dropping skb.
[  705.842022] blackhole_netdev_xmit(): Dropping skb.