[    2.355876] ip (276) used greatest stack depth: 12360 bytes left
[    2.400095] ip (280) used greatest stack depth: 12352 bytes left
[    9.697624] ip (786) used greatest stack depth: 12344 bytes left
[  637.065049] ip (24526) used greatest stack depth: 12312 bytes left
[ 1021.472459] blackhole_netdev_xmit(): Dropping skb.
[ 1021.472525] blackhole_netdev_xmit(): Dropping skb.
[ 1021.472557] blackhole_netdev_xmit(): Dropping skb.
[ 1021.472588] blackhole_netdev_xmit(): Dropping skb.