From patchwork Wed May 14 14:57:48 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 349190 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id E33B91400DA; Thu, 15 May 2014 22:00:17 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1WkuKX-00086m-7U; Thu, 15 May 2014 12:00:09 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Wkad0-0001mu-EZ for kernel-team@lists.ubuntu.com; Wed, 14 May 2014 14:57:54 +0000 Received: from [188.251.60.199] (helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Wkacw-0002qm-1W; Wed, 14 May 2014 14:57:50 +0000 From: Luis Henriques To: Vlastimil Babka Subject: [3.11.y.z extended stable] Patch "mm/compaction: make isolate_freepages start at pageblock boundary" has been added to staging queue Date: Wed, 14 May 2014 15:57:48 +0100 Message-Id: <1400079468-16679-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.11 X-Mailman-Approved-At: Thu, 15 May 2014 12:00:07 +0000 Cc: Christoph Lameter , Sunghwan Yun , Andrew Morton , Bartlomiej Zolnierkiewicz , Rik van Riel , Michal Nazarewicz , Heesub Shin , Minchan Kim , kernel-team@lists.ubuntu.com, Dongjun Shin , Mel Gorman , Joonsoo Kim , Linus Torvalds , Naoya Horiguchi X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled mm/compaction: make isolate_freepages start at pageblock boundary to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From d3cf1fbe9a0de6e049a39168c4f38fafcec86fd3 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 6 May 2014 12:50:03 -0700 Subject: mm/compaction: make isolate_freepages start at pageblock boundary commit 49e068f0b73dd042c186ffa9b420a9943e90389a upstream. The compaction freepage scanner implementation in isolate_freepages() starts by taking the current cc->free_pfn value as the first pfn. In a for loop, it scans from this first pfn to the end of the pageblock, and then subtracts pageblock_nr_pages from the first pfn to obtain the first pfn for the next for loop iteration. This means that when cc->free_pfn starts at offset X rather than being aligned on pageblock boundary, the scanner will start at offset X in all scanned pageblock, ignoring potentially many free pages. Currently this can happen when a) zone's end pfn is not pageblock aligned, or b) through zone->compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled and a hole spanning the beginning of a pageblock This patch fixes the problem by aligning the initial pfn in isolate_freepages() to pageblock boundary. This also permits replacing the end-of-pageblock alignment within the for loop with a simple pageblock_nr_pages increment. Signed-off-by: Vlastimil Babka Reported-by: Heesub Shin Acked-by: Minchan Kim Cc: Mel Gorman Acked-by: Joonsoo Kim Cc: Bartlomiej Zolnierkiewicz Cc: Michal Nazarewicz Cc: Naoya Horiguchi Cc: Christoph Lameter Acked-by: Rik van Riel Cc: Dongjun Shin Cc: Sunghwan Yun Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- mm/compaction.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) -- 1.9.1 diff --git a/mm/compaction.c b/mm/compaction.c index 18a90b4..46e2f96 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -657,16 +657,20 @@ static void isolate_freepages(struct zone *zone, struct compact_control *cc) { struct page *page; - unsigned long high_pfn, low_pfn, pfn, z_end_pfn, end_pfn; + unsigned long high_pfn, low_pfn, pfn, z_end_pfn; int nr_freepages = cc->nr_freepages; struct list_head *freelist = &cc->freepages; /* * Initialise the free scanner. The starting point is where we last - * scanned from (or the end of the zone if starting). The low point - * is the end of the pageblock the migration scanner is using. + * successfully isolated from, zone-cached value, or the end of the + * zone when isolating for the first time. We need this aligned to + * the pageblock boundary, because we do pfn -= pageblock_nr_pages + * in the for loop. + * The low boundary is the end of the pageblock the migration scanner + * is using. */ - pfn = cc->free_pfn; + pfn = cc->free_pfn & ~(pageblock_nr_pages-1); low_pfn = cc->migrate_pfn + pageblock_nr_pages; /* @@ -686,6 +690,7 @@ static void isolate_freepages(struct zone *zone, for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages; pfn -= pageblock_nr_pages) { unsigned long isolated; + unsigned long end_pfn; if (!pfn_valid(pfn)) continue; @@ -713,13 +718,10 @@ static void isolate_freepages(struct zone *zone, isolated = 0; /* - * As pfn may not start aligned, pfn+pageblock_nr_page - * may cross a MAX_ORDER_NR_PAGES boundary and miss - * a pfn_valid check. Ensure isolate_freepages_block() - * only scans within a pageblock + * Take care when isolating in last pageblock of a zone which + * ends in the middle of a pageblock. */ - end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); - end_pfn = min(end_pfn, z_end_pfn); + end_pfn = min(pfn + pageblock_nr_pages, z_end_pfn); isolated = isolate_freepages_block(cc, pfn, end_pfn, freelist, false); nr_freepages += isolated;