From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx111.postini.com [74.125.245.111]) by kanga.kvack.org (Postfix) with SMTP id 5C50F6B0044 for ; Tue, 9 Oct 2012 07:10:28 -0400 (EDT) Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MBM00GU2HOSZ480@mailout3.samsung.com> for linux-mm@kvack.org; Tue, 09 Oct 2012 20:10:26 +0900 (KST) Received: from amdc1032.localnet ([106.116.147.136]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0MBM00E2LHPB7T40@mmp2.samsung.com> for linux-mm@kvack.org; Tue, 09 Oct 2012 20:10:26 +0900 (KST) From: Bartlomiej Zolnierkiewicz Subject: Re: CMA broken in next-20120926 Date: Tue, 09 Oct 2012 13:08:30 +0200 References: <20120928105113.GA18883@avionic-0098.mockup.avionic-design.de> <201210091040.10811.b.zolnierkie@samsung.com> <20121009101143.GQ29125@suse.de> In-reply-to: <20121009101143.GQ29125@suse.de> MIME-version: 1.0 Content-type: Text/Plain; charset=us-ascii Content-transfer-encoding: 7bit Message-id: <201210091308.30306.b.zolnierkie@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Minchan Kim , Thierry Reding , Peter Ujfalusi , Andrew Morton , Marek Szyprowski , Michal Nazarewicz , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kyungmin Park , Mark Brown On Tuesday 09 October 2012 12:11:43 Mel Gorman wrote: > On Tue, Oct 09, 2012 at 10:40:10AM +0200, Bartlomiej Zolnierkiewicz wrote: > > I also need following patch to make CONFIG_CMA=y && CONFIG_COMPACTION=y case > > work: > > > > From: Bartlomiej Zolnierkiewicz > > Subject: [PATCH] mm: compaction: cache if a pageblock was scanned and no pages were isolated - cma fix > > > > Patch "mm: compaction: cache if a pageblock was scanned and no pages > > were isolated" needs a following fix to successfully boot next-20121002 > > kernel (same with next-20121008) with CONFIG_CMA=y and CONFIG_COMPACTION=y > > (with applied -fix1, -fix2, -fix3 patches from Mel Gorman and also with > > cmatest module from Thierry Reding compiled in). > > > > Why is it needed to make it boot? CMA should not care about the It boots without Thierry's cmatest module but then fails on CMA allocation attempt (I used out-of-tree /dev/cma_test interface to generate CMA allocation request from user-space). > PG_migrate_skip hint being set because it should always ignore it in > alloc_contig_range() due to cc->ignore_skip_hint. It's not obvious to > me why this fixes a boot failure and I wonder if it's papering over some > underlying problem. Can you provide more details please? I just compared CONFIG_COMPACTION=n and =y cases initially, figured out the difference and did the change. However on a closer look it seems that {get,clear,set}_pageblock_skip() use incorrect bit ranges (please compare to bit ranges used by {get,set}_pageblock_flags() used for migration types) and can overwrite pageblock migratetype of the next pageblock in the bitmap (I wonder how could this code ever worked before?). > > Signed-off-by: Bartlomiej Zolnierkiewicz > > Signed-off-by: Kyungmin Park > > --- > > mm/compaction.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > Index: b/mm/compaction.c > > =================================================================== > > --- a/mm/compaction.c 2012-10-08 18:10:53.491679716 +0200 > > +++ b/mm/compaction.c 2012-10-08 18:11:33.615679713 +0200 > > @@ -117,7 +117,8 @@ static void update_pageblock_skip(struct > > bool migrate_scanner) > > { > > struct zone *zone = cc->zone; > > - if (!page) > > + > > + if (!page || cc->ignore_skip_hint) > > return; > > > > if (!nr_isolated) { The patch below also fixes the issue for me: From: Bartlomiej Zolnierkiewicz Subject: [PATCH] mm: compaction: fix bit ranges in {get,clear,set}_pageblock_skip() {get,clear,set}_pageblock_skip() use incorrect bit ranges (please compare to bit ranges used by {get,set}_pageblock_flags() used for migration types) and can overwrite pageblock migratetype of the next pageblock in the bitmap. Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: Kyungmin Park --- include/linux/pageblock-flags.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: b/include/linux/pageblock-flags.h =================================================================== --- a/include/linux/pageblock-flags.h 2012-10-09 12:50:20.366340001 +0200 +++ b/include/linux/pageblock-flags.h 2012-10-09 12:50:31.794339996 +0200 @@ -71,13 +71,13 @@ void set_pageblock_flags_group(struct pa #ifdef CONFIG_COMPACTION #define get_pageblock_skip(page) \ get_pageblock_flags_group(page, PB_migrate_skip, \ - PB_migrate_skip + 1) + PB_migrate_skip) #define clear_pageblock_skip(page) \ set_pageblock_flags_group(page, 0, PB_migrate_skip, \ - PB_migrate_skip + 1) + PB_migrate_skip) #define set_pageblock_skip(page) \ set_pageblock_flags_group(page, 1, PB_migrate_skip, \ - PB_migrate_skip + 1) + PB_migrate_skip) #endif /* CONFIG_COMPACTION */ #define get_pageblock_flags(page) \ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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