[    1.936618] ip (245) used greatest stack depth: 12304 bytes left
[  628.417628] ip (15847) used greatest stack depth: 12272 bytes left
[  773.548404] blackhole_netdev_xmit(): Dropping skb.
[  773.548466] blackhole_netdev_xmit(): Dropping skb.
[  773.548516] blackhole_netdev_xmit(): Dropping skb.
[  773.548567] blackhole_netdev_xmit(): Dropping skb.