[    1.598199] ip (242) used greatest stack depth: 12352 bytes left
[    2.038818] ip (276) used greatest stack depth: 12320 bytes left
[    9.442804] ip (1086) used greatest stack depth: 12048 bytes left
[  841.305982] blackhole_netdev_xmit(): Dropping skb.
[  841.306042] blackhole_netdev_xmit(): Dropping skb.
[  841.306087] blackhole_netdev_xmit(): Dropping skb.
[  841.306135] blackhole_netdev_xmit(): Dropping skb.