[    1.684173] ip (246) used greatest stack depth: 12352 bytes left
[    2.091424] ip (277) used greatest stack depth: 12320 bytes left
[    4.745058] ip (407) used greatest stack depth: 12304 bytes left
[    5.219992] ip (444) used greatest stack depth: 12272 bytes left
[  634.052331] ip (16678) used greatest stack depth: 12224 bytes left
[  665.380888] blackhole_netdev_xmit(): Dropping skb.
[  665.380942] blackhole_netdev_xmit(): Dropping skb.
[  665.380976] blackhole_netdev_xmit(): Dropping skb.
[  665.381015] blackhole_netdev_xmit(): Dropping skb.