[    1.728953] ip (244) used greatest stack depth: 12352 bytes left
[    2.141604] ip (275) used greatest stack depth: 12320 bytes left
[    7.296030] ip (647) used greatest stack depth: 12160 bytes left
[  750.997232] blackhole_netdev_xmit(): Dropping skb.
[  750.997302] blackhole_netdev_xmit(): Dropping skb.
[  750.997341] blackhole_netdev_xmit(): Dropping skb.
[  750.997385] blackhole_netdev_xmit(): Dropping skb.