[    1.895242] ip (243) used greatest stack depth: 12352 bytes left
[    2.495720] ip (277) used greatest stack depth: 12320 bytes left
[  638.987634] ip (22225) used greatest stack depth: 12304 bytes left
[  720.781256] blackhole_netdev_xmit(): Dropping skb.
[  720.781330] blackhole_netdev_xmit(): Dropping skb.
[  720.781378] blackhole_netdev_xmit(): Dropping skb.
[  720.781428] blackhole_netdev_xmit(): Dropping skb.