From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Date: Mon, 22 Sep 2008 20:57:52 +0000 (-0700)
Subject: memcg: check under limit at shrink_usage
X-Git-Tag: v2.6.27-rc8~37
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a10cebf56ca7e7c034d1b6646230c6553e478967;p=pandora-kernel.git

memcg: check under limit at shrink_usage

Current memory cgroup(both in mainline and -mm) doesn't account swap
caches as memory(swap cache support is dropped temporarily now).

So try_to_free_mem_cgroup_pages doesn't reflect the count of pages that
have been moved to swap cache.

But this makes mem_cgroup_shrink_usage fail easily if most of the pages
are anon/shmem, and then shmem_getpage returns -ENOMEM and the process
will be killed.

This patch adds res_counter_check_under_limit to avoid these cases.

BTW, even if swap cache support is enabled again, if a process is moved to
another cgroup, which has been just made, between precharge and
shrink_usage in shmem_getpage, shrink_usage may fail just because there is
no pages to reclaim.

So this change would make sense anyway.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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