[    2.538091] ip (275) used greatest stack depth: 12328 bytes left
[  636.014283] ip (17520) used greatest stack depth: 12312 bytes left
[  710.434048] blackhole_netdev_xmit(): Dropping skb.
[  710.434151] blackhole_netdev_xmit(): Dropping skb.
[  710.434191] blackhole_netdev_xmit(): Dropping skb.
[  710.434228] blackhole_netdev_xmit(): Dropping skb.