linux-kernel - [PATCH] memcg: reset to root_mem

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Message-Id: <20111219165146.4d72f1bb.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Mon, 19 Dec 2011 16:51:46 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>, cgroups@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hannes@...xchg.org" <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>
Subject: [PATCH] memcg: reset to root_mem_cgroup at bypassing

>From d620ff605a3a592c2b1de3a046498ce5cd3d3c50 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Date: Mon, 19 Dec 2011 16:55:10 +0900
Subject: [PATCH 2/2] memcg: reset lru to root_mem_cgroup in special cases.

This patch is a fix for memcg-simplify-lru-handling-by-new-rule.patch

After the patch, all pages which will be onto LRU must have sane
pc->mem_cgroup. But, in special case, it's not set.

If task->mm is NULL or task is TIF_MEMDIE or fatal_signal_pending(),
try_charge() is bypassed and the new charge will not be charged. And
pc->mem_cgroup is unset even if the page will be used/mapped and added
to LRU. To avoid this,  this patch charges such pages to root_mem_cgroup,
then, pc->mem_cgroup will be handled correctly.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
 mm/memcontrol.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0d6d21c..9268e8e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2324,7 +2324,7 @@ nomem:
 	*ptr = NULL;
 	return -ENOMEM;
 bypass:
-	*ptr = NULL;
+	*ptr = root_mem_cgroup;
 	return 0;
 }
 
-- 
1.7.4.1


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