linux-kernel - [PATCH -mm 1/4] oom: select_bad_process: check PF

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Message-ID: <20100402183132.GB31723@redhat.com>
Date:	Fri, 2 Apr 2010 20:31:32 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	anfei <anfei.zhou@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	nishimura@....nes.nec.co.jp,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH -mm 1/4] oom: select_bad_process: check PF_KTHREAD instead
	of !mm to skip kthreads

select_bad_process() thinks a kernel thread can't have ->mm != NULL,
this is not true due to use_mm().

Change the code to check PF_KTHREAD.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---

 mm/oom_kill.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- MM/mm/oom_kill.c~1_FLITER_OUT_KTHREADS	2010-03-31 17:47:14.000000000 +0200
+++ MM/mm/oom_kill.c	2010-04-02 18:51:05.000000000 +0200
@@ -290,8 +290,8 @@ static struct task_struct *select_bad_pr
 	for_each_process(p) {
 		unsigned int points;
 
-		/* skip the init task */
-		if (is_global_init(p))
+		/* skip the init task and kthreads */
+		if (is_global_init(p) || (p->flags & PF_KTHREAD))
 			continue;
 		if (mem && !task_in_mem_cgroup(p, mem))
 			continue;
@@ -331,8 +331,7 @@ static struct task_struct *select_bad_pr
 		}
 
 		/*
-		 * skip kernel threads and tasks which have already released
-		 * their mm.
+		 * skip the tasks which have already released their mm.
 		 */
 		if (!p->mm)
 			continue;

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