[    2.679847] ip (280) used greatest stack depth: 12344 bytes left
[  639.475023] ip (23868) used greatest stack depth: 12304 bytes left
[  989.698865] blackhole_netdev_xmit(): Dropping skb.
[  989.698937] blackhole_netdev_xmit(): Dropping skb.
[  989.698970] blackhole_netdev_xmit(): Dropping skb.
[  989.699001] blackhole_netdev_xmit(): Dropping skb.