[    1.921948] ip (240) used greatest stack depth: 12376 bytes left
[    2.484542] ip (274) used greatest stack depth: 12344 bytes left
[    9.909414] ip (915) used greatest stack depth: 12328 bytes left
[  632.741023] ip (6152) used greatest stack depth: 12184 bytes left
[ 1187.488640] blackhole_netdev_xmit(): Dropping skb.
[ 1187.488716] blackhole_netdev_xmit(): Dropping skb.
[ 1187.488760] blackhole_netdev_xmit(): Dropping skb.
[ 1187.488806] blackhole_netdev_xmit(): Dropping skb.