[    1.534250] ip (240) used greatest stack depth: 12544 bytes left
[    1.554197] ip (243) used greatest stack depth: 12352 bytes left
[    1.882917] ip (274) used greatest stack depth: 12320 bytes left
[    4.592983] ip (453) used greatest stack depth: 12144 bytes left
[ 1203.329851] blackhole_netdev_xmit(): Dropping skb.
[ 1203.329926] blackhole_netdev_xmit(): Dropping skb.
[ 1203.329981] blackhole_netdev_xmit(): Dropping skb.
[ 1203.330033] blackhole_netdev_xmit(): Dropping skb.