[    1.637262] ip (239) used greatest stack depth: 12352 bytes left
[    2.055959] ip (273) used greatest stack depth: 12320 bytes left
[  323.198957] ip (4394) used greatest stack depth: 12048 bytes left
[  969.661740] blackhole_netdev_xmit(): Dropping skb.
[  969.661812] blackhole_netdev_xmit(): Dropping skb.
[  969.661851] blackhole_netdev_xmit(): Dropping skb.
[  969.661886] blackhole_netdev_xmit(): Dropping skb.