linux-kernel - Re: oomkiller over-ambitious after "vmscan: make mapped executable pages the first class citizen" (bisected)

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Date:	Tue, 13 Oct 2009 07:50:36 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Wu Fengguang <fengguang.wu@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>, stable@...nel.org
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Elladan <elladan@...imo.com>, Nick Piggin <npiggin@...e.de>,
	Andi Kleen <andi@...stfloor.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan.kim@...il.com>
Subject: Re: oomkiller over-ambitious after "vmscan: make mapped executable pages the first class citizen" (bisected)

Am Dienstag 13 Oktober 2009 04:26:50 schrieb Wu Fengguang:
[...]

> Can you try this patch? Thanks!

Yes, this patch solves the problem. In fact, my test case was a reduced version
of KVM on s390 and it helps there as well.

Since the problem also affects 2.6.31 I added stable.

I agree with Rik, that this patch should go to Linus quickly, what is the best 
way? Andrew?

> ---
> vmscan: limit VM_EXEC protection to file pages
> 
> It is possible to have !Anon but SwapBacked pages, and some apps could
> create huge number of such pages with MAP_SHARED|MAP_ANONYMOUS. These
> pages go into the ANON lru list, and hence shall not be protected: we
> only care mapped executable files. Failing to do so may trigger OOM.
> 
> Reported-by: Christian Borntraeger <borntraeger@...ibm.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>

Tested-by: Christian Borntraeger <borntraeger@...ibm.com>

> ---
>  mm/vmscan.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- linux.orig/mm/vmscan.c	2009-10-13 09:49:05.000000000 +0800
> +++ linux/mm/vmscan.c	2009-10-13 09:49:37.000000000 +0800
> @@ -1356,7 +1356,7 @@ static void shrink_active_list(unsigned
>  			 * IO, plus JVM can create lots of anon VM_EXEC pages,
>  			 * so we ignore them here.
>  			 */
> -			if ((vm_flags & VM_EXEC) && !PageAnon(page)) {
> +			if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
>  				list_add(&page->lru, &l_active);
>  				continue;
>  			}
> 
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