[    1.962399] ip (245) used greatest stack depth: 12352 bytes left
[    2.515019] ip (276) used greatest stack depth: 12320 bytes left
[   20.678095] ip (2218) used greatest stack depth: 12272 bytes left
[   20.831113] ip (2228) used greatest stack depth: 12160 bytes left
[  897.728574] blackhole_netdev_xmit(): Dropping skb.
[  897.728643] blackhole_netdev_xmit(): Dropping skb.
[  897.728685] blackhole_netdev_xmit(): Dropping skb.
[  897.728722] blackhole_netdev_xmit(): Dropping skb.