These are two additional handlers for OOM situation.

oom_panic - will make kernel panic in oom condition. It is usefull for some 
embedded developers as I understand.

oom_kill_parent - keeps tracks of parents whose children were killed in the 
past. When configurable (sysctl) threshold is passed, parent itself is 
killed. Also, parent sins are expired after some time (also configurable).

Regards,
Tvrtko