Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756634Ab1FFOUG (ORCPT ); Mon, 6 Jun 2011 10:20:06 -0400 Received: from mail-px0-f179.google.com ([209.85.212.179]:61316 "EHLO mail-px0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751164Ab1FFOUD (ORCPT ); Mon, 6 Jun 2011 10:20:03 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=dZuObfGuS/9ARcVpMFio1hdx3x3mWGeIImAObYvQFMDNGOoBOUiWCD6FxVZTkUoJJr uwk8MDTPRIppT5sM/ImaUd/+SoF+WwdSvNwJRw05Oo6lFI+85gAfnjx6mAzeuA5PQN/k LBkEXMc9UGrji45ms9W/sucAUcSLkOTdCOyXI= Date: Mon, 6 Jun 2011 23:19:52 +0900 From: Minchan Kim To: Mel Gorman Cc: Andrea Arcangeli , 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: <20110606141952.GE1686@barrios-laptop> References: <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> <20110606103924.GD5247@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110606103924.GD5247@suse.de> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2247 Lines: 73 On Mon, Jun 06, 2011 at 11:39:24AM +0100, Mel Gorman wrote: > 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)) I like this. but as it's "and" operation, CPU have to execute two condition comparison. but how about below? if (!PageSwapCache(page) && PageSwapBacked(page)) PageSwapCache implys PageSwapBacked so we can handle non-swapbacked pages as just 1 comparison. > > ? > > > --- > > > > 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 -- Kind regards Minchan Kim -- 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/