linux-kernel - [PATCH 1/2] memcg: mm_update_next

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Message-ID: <20140418172653.GB13323@redhat.com>
Date:	Fri, 18 Apr 2014 19:26:53 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Chiang <pchiang@...dia.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Balbir Singh <bsingharora@...il.com>,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>
Cc:	"ccross@...roid.com" <ccross@...roid.com>,
	"lizefan@...wei.com" <lizefan@...wei.com>,
	"tj@...nel.org" <tj@...nel.org>, "pavel@....cz" <pavel@....cz>,
	"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
	"guillaume@...infr.org" <guillaume@...infr.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] memcg: mm_update_next_owner() should skip kthreads

"Search through everything else" in mm_update_next_owner() can
hit a kthread which adopted this "mm" via use_mm(), it should
not be used as mm->owner. Add the PF_KTHREAD check.

While at it, change this code to use for_each_process_thread()
instead of deprecated do_each_thread/while_each_thread.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/exit.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index ad7183a..e270d2a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -356,14 +356,12 @@ retry:
 	}
 
 	/*
-	 * Search through everything else. We should not get
-	 * here often
+	 * Search through everything else, we should not get here often.
 	 */
-	do_each_thread(g, c) {
-		if (c->mm == mm)
+	for_each_process_thread(g, c) {
+		if (!(c->flags & PF_KTHREAD) && c->mm == mm)
 			goto assign_new_owner;
-	} while_each_thread(g, c);
-
+	}
 	read_unlock(&tasklist_lock);
 	/*
 	 * We found no owner yet mm_users > 1: this implies that we are
-- 
1.5.5.1


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