Cgroup OOM bug

[Jeremy Hanmer]

I've found a reproducible case where you can create an infinite loop inside the oom killer if you create a cgroup with a single process that has oom_adj=-17 and trigger an OOM situation inside that cgroup.

It seems that oom_adj should probably be ignored in the case where it makes the OOM situation unsolvable.  Here's an excerpt from the console output when the bug is triggered:

Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child
Memory cgroup out of memory: kill process 25306 (memeater) score 0 or a child