linux-kernel - [PATCH -mm 2/4] oom: select_bad_process: PF_EXITING check should take ->mm into account

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100402183216.GC31723@redhat.com>
Date:	Fri, 2 Apr 2010 20:32:16 +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 2/4] oom: select_bad_process: PF_EXITING check should
	take ->mm into account

select_bad_process() checks PF_EXITING to detect the task which
is going to release its memory, but the logic is very wrong.

	- a single process P with the dead group leader disables
	  select_bad_process() completely, it will always return
	  ERR_PTR() while P can live forever

	- if the PF_EXITING task has already released its ->mm
	  it doesn't make sense to expect it is goiing to free
	  more memory (except task_struct/etc)

Change the code to ignore the PF_EXITING tasks without ->mm.

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

 mm/oom_kill.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- MM/mm/oom_kill.c~2_FIX_PF_EXITING	2010-04-02 18:51:05.000000000 +0200
+++ MM/mm/oom_kill.c	2010-04-02 18:58:37.000000000 +0200
@@ -322,7 +322,7 @@ static struct task_struct *select_bad_pr
 		 * the process of exiting and releasing its resources.
 		 * Otherwise we could get an easy OOM deadlock.
 		 */
-		if (p->flags & PF_EXITING) {
+		if ((p->flags & PF_EXITING) && p->mm) {
 			if (p != current)
 				return ERR_PTR(-1UL);
 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/