[    1.684025] ip (243) used greatest stack depth: 12352 bytes left
[    2.083195] ip (277) used greatest stack depth: 12320 bytes left
[    7.414351] ip (914) used greatest stack depth: 12304 bytes left
[  893.121624] blackhole_netdev_xmit(): Dropping skb.
[  893.121700] blackhole_netdev_xmit(): Dropping skb.
[  893.121743] blackhole_netdev_xmit(): Dropping skb.
[  893.121778] blackhole_netdev_xmit(): Dropping skb.