[    1.835812] ip (242) used greatest stack depth: 12376 bytes left
[    2.448099] ip (276) used greatest stack depth: 12360 bytes left
[    2.495654] ip (280) used greatest stack depth: 12352 bytes left
[    4.642063] ip (411) used greatest stack depth: 12328 bytes left
[  636.101500] ip (19788) used greatest stack depth: 12312 bytes left
[ 1077.654893] blackhole_netdev_xmit(): Dropping skb.
[ 1077.654965] blackhole_netdev_xmit(): Dropping skb.
[ 1077.655007] blackhole_netdev_xmit(): Dropping skb.
[ 1077.655054] blackhole_netdev_xmit(): Dropping skb.