thp, memcg: split hugepage for memcg oom on cow
authorDavid Rientjes <rientjes@google.com>
Tue, 29 May 2012 22:06:23 +0000 (15:06 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 17 Jan 2013 16:43:58 +0000 (08:43 -0800)
commit457a972f3038b8de2eba76dc4b7f9117f1084f7e
treea3ad8963628a1d5dd8d072f0bdc361d52fed3265
parentcdfcbd8d74fdfd7a0d55330a1b60411b153ae71b
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm/huge_memory.c
mm/memory.c