[    2.086733] ip (243) used greatest stack depth: 12352 bytes left
[    2.810131] ip (277) used greatest stack depth: 12320 bytes left
[  635.154190] ip (17879) used greatest stack depth: 12304 bytes left
[  649.196528] ip (19273) used greatest stack depth: 12272 bytes left
[  826.963032] blackhole_netdev_xmit(): Dropping skb.
[  826.963097] blackhole_netdev_xmit(): Dropping skb.
[  826.963129] blackhole_netdev_xmit(): Dropping skb.
[  826.963172] blackhole_netdev_xmit(): Dropping skb.