Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755016Ab1FFKja (ORCPT ); Mon, 6 Jun 2011 06:39:30 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34571 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752513Ab1FFKj2 (ORCPT ); Mon, 6 Jun 2011 06:39:28 -0400 Date: Mon, 6 Jun 2011 11:39:24 +0100 From: Mel Gorman To: Andrea Arcangeli Cc: Minchan Kim , akpm@linux-foundation.org, Ury Stankevich , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@kernel.org Subject: Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Message-ID: <20110606103924.GD5247@suse.de> References: <20110601191529.GY19505@random.random> <20110601214018.GC7306@suse.de> <20110601233036.GZ19505@random.random> <20110602010352.GD7306@suse.de> <20110602132954.GC19505@random.random> <20110602145019.GG7306@suse.de> <20110602153754.GF19505@random.random> <20110603020920.GA26753@suse.de> <20110603144941.GI7306@suse.de> <20110603154554.GK2802@random.random> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20110603154554.GK2802@random.random> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1786 Lines: 61 On Fri, Jun 03, 2011 at 05:45:54PM +0200, Andrea Arcangeli wrote: > On Fri, Jun 03, 2011 at 03:49:41PM +0100, Mel Gorman wrote: > > Right idea of the wrong zone being accounted for but wrong place. I > > think the following patch should fix the problem; > > Looks good thanks. > > I also found this bug during my debugging that made NR_SHMEM underflow. > > === > Subject: migrate: don't account swapcache as shmem > > From: Andrea Arcangeli > > swapcache will reach the below code path in migrate_page_move_mapping, > and swapcache is accounted as NR_FILE_PAGES but it's not accounted as > NR_SHMEM. > > Signed-off-by: Andrea Arcangeli Well spotted. Acked-by: Mel Gorman Minor nit. swapper_space is rarely referred to outside of the swap code. Might it be more readable to use /* * swapcache is accounted as NR_FILE_PAGES but it is not * accounted as NR_SHMEM * if (PageSwapBacked(page) && !PageSwapCache(page)) ? > --- > > diff --git a/mm/migrate.c b/mm/migrate.c > index e4a5c91..2597a27 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -288,7 +288,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, > */ > __dec_zone_page_state(page, NR_FILE_PAGES); > __inc_zone_page_state(newpage, NR_FILE_PAGES); > - if (PageSwapBacked(page)) { > + if (mapping != &swapper_space && PageSwapBacked(page)) { > __dec_zone_page_state(page, NR_SHMEM); > __inc_zone_page_state(newpage, NR_SHMEM); > } > > -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/