[    1.680956] ip (241) used greatest stack depth: 12352 bytes left
[    2.078812] ip (275) used greatest stack depth: 12320 bytes left
[    4.821185] ip (412) used greatest stack depth: 12304 bytes left
[  640.008801] ip (8696) used greatest stack depth: 12160 bytes left
[  885.407908] blackhole_netdev_xmit(): Dropping skb.
[  885.407960] blackhole_netdev_xmit(): Dropping skb.
[  885.407990] blackhole_netdev_xmit(): Dropping skb.
[  885.408015] blackhole_netdev_xmit(): Dropping skb.