[    1.687322] ip (245) used greatest stack depth: 12352 bytes left
[    2.127372] ip (276) used greatest stack depth: 12320 bytes left
[  322.501164] ip (5461) used greatest stack depth: 12272 bytes left
[  664.770083] blackhole_netdev_xmit(): Dropping skb.
[  664.770143] blackhole_netdev_xmit(): Dropping skb.
[  664.770175] blackhole_netdev_xmit(): Dropping skb.
[  664.770209] blackhole_netdev_xmit(): Dropping skb.