From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932306AbXCNQNb (ORCPT ); Wed, 14 Mar 2007 12:13:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932289AbXCNQNb (ORCPT ); Wed, 14 Mar 2007 12:13:31 -0400 Received: from calculon.skynet.ie ([193.1.99.88]:41622 "EHLO calculon.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932112AbXCNQNa (ORCPT ); Wed, 14 Mar 2007 12:13:30 -0400 Date: Wed, 14 Mar 2007 16:13:27 +0000 To: Bjorn Helgaas Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: 2.6.21-rc3-mm2 (oops in move_freepages) Message-ID: <20070314161327.GA14416@skynet.ie> References: <20070307201915.4d579113.akpm@linux-foundation.org> <200703132152.10136.bjorn.helgaas@hp.com> <20070314094454.GA1652@skynet.ie> <200703140911.16537.bjorn.helgaas@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <200703140911.16537.bjorn.helgaas@hp.com> User-Agent: Mutt/1.5.9i From: mel@skynet.ie (Mel Gorman) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On (14/03/07 09:11), Bjorn Helgaas didst pronounce: > On Wednesday 14 March 2007 03:44, Mel Gorman wrote: > > Please try the following patch from Yasunori Goto. > > ... > > --- current_test.orig/mm/page_alloc.c 2007-03-08 15:44:10.000000000 +0900 > > +++ current_test/mm/page_alloc.c 2007-03-08 16:17:29.000000000 +0900 > > @@ -707,7 +707,7 @@ int move_freepages(struct zone *zone, > > unsigned long order; > > int blocks_moved = 0; > > > > - BUG_ON(page_zone(start_page) != page_zone(end_page)); > > + BUG_ON(page_zone(start_page) != page_zone(end_page - 1)); > > > > I should have mentioned that I already tried this patch. The > oops still occurs, although now it's when loading the value > pointed to by "end_page - 1" instead of "end_page". Ok. This looks like another case of HOLES_IN_ZONE hilarity with page_zone(). As I take a new look at the BUG_ON check in move_freepages(), it isn't even necessary as move_freepages_block() already checks the zone boundaries. At a later date when the code has survived a while without new bug reports, I'll submit a patch that simply deletes this check because it should be redundant. Just in case, I'd like to preserve the check in the non-HOLES_IN_ZONE case for now. Can you try this patch please? It should apply on top of Yasunori Goto's patch. Signed-off-by: Mel Gorman diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.21-rc3-mm2-goto/mm/page_alloc.c linux-2.6.21-rc3-mm2-bjorn_testfix/mm/page_alloc.c --- linux-2.6.21-rc3-mm2-goto/mm/page_alloc.c 2007-03-14 16:07:23.000000000 +0000 +++ linux-2.6.21-rc3-mm2-bjorn_testfix/mm/page_alloc.c 2007-03-14 16:01:00.000000000 +0000 @@ -707,7 +707,15 @@ int move_freepages(struct zone *zone, unsigned long order; int blocks_moved = 0; +#ifndef CONFIG_HOLES_IN_ZONE + /* + * page_zone is not safe to call in this context when + * CONFIG_HOLES_IN_ZONE is set but this bug check is + * redundant anyway as we check zone boundaries in + * move_freepages_block() + */ BUG_ON(page_zone(start_page) != page_zone(end_page - 1)); +#endif for (page = start_page; page < end_page;) { if (!PageBuddy(page)) {