[    1.700397] ip (240) used greatest stack depth: 12352 bytes left
[    2.147047] ip (274) used greatest stack depth: 12320 bytes left
[  624.070737] ip (14941) used greatest stack depth: 12304 bytes left
[  633.760091] ip (16368) used greatest stack depth: 12160 bytes left
[  849.368076] blackhole_netdev_xmit(): Dropping skb.
[  849.368133] blackhole_netdev_xmit(): Dropping skb.
[  849.368170] blackhole_netdev_xmit(): Dropping skb.
[  849.368208] blackhole_netdev_xmit(): Dropping skb.
[  940.005871] ip (23280) used greatest stack depth: 12032 bytes left