linux-kernel - [patch 3/3] memcg: never OOM when charging huge pages

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Message-ID: <20110127134703.GB14309@cmpxchg.org>
Date:	Thu, 27 Jan 2011 14:47:03 +0100
From:	Johannes Weiner <hannes@...xchg.org>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
	"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: [patch 3/3] memcg: never OOM when charging huge pages

Huge page coverage should obviously have less priority than the
continued execution of a process.

Never kill a process when charging it a huge page fails.  Instead,
give up after the first failed reclaim attempt and fall back to
regular pages.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/memcontrol.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 17c4e36..2945649 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1890,6 +1890,13 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
 	int csize = max(CHARGE_SIZE, (unsigned long) page_size);
 
 	/*
+	 * Do not OOM on huge pages.  Fall back to regular pages after
+	 * the first failed reclaim attempt.
+	 */
+	if (page_size > PAGE_SIZE)
+		oom = false;
+
+	/*
 	 * Unlike gloval-vm's OOM-kill, we're not in memory shortage
 	 * in system level. So, allow to go ahead dying process in addition to
 	 * MEMDIE process.
-- 
1.7.3.5

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