[    1.930359] ip (249) used greatest stack depth: 12376 bytes left
[    2.505180] ip (280) used greatest stack depth: 12344 bytes left
[   12.649264] ip (1049) used greatest stack depth: 12328 bytes left
[   13.411647] ip (1092) used greatest stack depth: 12064 bytes left
[  717.299538] blackhole_netdev_xmit(): Dropping skb.
[  717.299628] blackhole_netdev_xmit(): Dropping skb.
[  717.299678] blackhole_netdev_xmit(): Dropping skb.
[  717.299719] blackhole_netdev_xmit(): Dropping skb.