A memory cgroup in trouble (oom-killer disabled, forkbomb) can potentially livelock tasks outside the group that share the same data (shared libraries e.g.).
When COW-breaking a page, the copy is allocated and charged while the original page is locked. If the charging requires reclaim or oom-killing, other tasks are tripped up when trying to access and lock the same COW page, causing indefinite stalls.
Since RHEL 6.3 External Beta has begun, and this bug remains
unresolved, it has been rejected as it is not proposed as
exception or blocker.
Red Hat invites you to ask your support representative to
propose this request, if appropriate and relevant, in the
next release of Red Hat Enterprise Linux.