linux-kernel - [patch -mm v2] oom: exclude tasks with badness score of 0 from being selected

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Message-ID: <alpine.DEB.2.00.1004021421060.5599@chino.kir.corp.google.com>
Date:	Fri, 2 Apr 2010 14:22:16 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Oleg Nesterov <oleg@...hat.com>, anfei <anfei.zhou@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	nishimura@....nes.nec.co.jp,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [patch -mm v2] oom: exclude tasks with badness score of 0 from being
 selected

An oom_badness() score of 0 means "never kill" according to
Documentation/filesystems/proc.txt, so exclude it from being selected for
kill.  These tasks have either detached their p->mm or are set to
OOM_DISABLE.

Also removes an unnecessary initialization of points to 0 in
mem_cgroup_out_of_memory(), select_bad_process() does this already.

Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/oom_kill.c |   13 ++-----------
 1 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -326,17 +326,8 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
 			*ppoints = 1000;
 		}
 
-		/*
-		 * skip kernel threads and tasks which have already released
-		 * their mm.
-		 */
-		if (!p->mm)
-			continue;
-		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
-			continue;
-
 		points = oom_badness(p, totalpages);
-		if (points > *ppoints || !chosen) {
+		if (points > *ppoints) {
 			chosen = p;
 			*ppoints = points;
 		}
@@ -478,7 +469,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
 {
 	unsigned long limit;
-	unsigned int points = 0;
+	unsigned int points;
 	struct task_struct *p;
 
 	if (sysctl_panic_on_oom == 2)
--
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