From: David Rientjes <rientjes@google.com>
Date: Tue, 29 May 2012 22:06:23 +0000 (-0700)
Subject: thp, memcg: split hugepage for memcg oom on cow
X-Git-Tag: v3.2.36~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=505bd8dcba128970db6fed2eca126f9e11a44290;p=pandora-kernel.git

thp, memcg: split hugepage for memcg oom on cow

commit 1f1d06c34f7675026326cd9f39ff91e4555cf355 upstream.

On COW, a new hugepage is allocated and charged to the memcg.  If the
system is oom or the charge to the memcg fails, however, the fault
handler will return VM_FAULT_OOM which results in an oom kill.

Instead, it's possible to fallback to splitting the hugepage so that the
COW results only in an order-0 page being allocated and charged to the
memcg which has a higher liklihood to succeed.  This is expensive
because the hugepage must be split in the page fault handler, but it is
much better than unnecessarily oom killing a process.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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