From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754442Ab1HAXaX (ORCPT ); Mon, 1 Aug 2011 19:30:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38952 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754170Ab1HAX1s (ORCPT ); Mon, 1 Aug 2011 19:27:48 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Aug 1 16:20:56 2011 Message-Id: <20110801232056.622155467@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Mon, 01 Aug 2011 16:19:15 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andrea Arcangeli , Thomas Sattler , Mel Gorman Subject: [60/70] [stable] [PATCH 3/3] mm: compaction: abort compaction if too many pages are isolated and caller is asynchronous V2 In-Reply-To: <20110801232124.GA15313@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.39-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mel Gorman commit: f9e35b3b41f47c4e17d8132edbcab305a6aaa4b0 upstream Asynchronous compaction is used when promoting to huge pages. This is all very nice but if there are a number of processes in compacting memory, a large number of pages can be isolated. An "asynchronous" process can stall for long periods of time as a result with a user reporting that firefox can stall for 10s of seconds. This patch aborts asynchronous compaction if too many pages are isolated as it's better to fail a hugepage promotion than stall a process. [minchan.kim@gmail.com: return COMPACT_PARTIAL for abort] Reported-and-tested-by: Ury Stankevich Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Reviewed-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/compaction.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) --- a/mm/compaction.c +++ b/mm/compaction.c @@ -251,11 +251,18 @@ static bool too_many_isolated(struct zon return isolated > (inactive + active) / 2; } +/* possible outcome of isolate_migratepages */ +typedef enum { + ISOLATE_ABORT, /* Abort compaction now */ + ISOLATE_NONE, /* No pages isolated, continue scanning */ + ISOLATE_SUCCESS, /* Pages isolated, migrate */ +} isolate_migrate_t; + /* * Isolate all pages that can be migrated from the block pointed to by * the migrate scanner within compact_control. */ -static unsigned long isolate_migratepages(struct zone *zone, +static isolate_migrate_t isolate_migratepages(struct zone *zone, struct compact_control *cc) { unsigned long low_pfn, end_pfn; @@ -272,7 +279,7 @@ static unsigned long isolate_migratepage /* Do not cross the free scanner or scan within a memory hole */ if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) { cc->migrate_pfn = end_pfn; - return 0; + return ISOLATE_NONE; } /* @@ -281,10 +288,14 @@ static unsigned long isolate_migratepage * delay for some time until fewer pages are isolated */ while (unlikely(too_many_isolated(zone))) { + /* async migration should just abort */ + if (!cc->sync) + return ISOLATE_ABORT; + congestion_wait(BLK_RW_ASYNC, HZ/10); if (fatal_signal_pending(current)) - return 0; + return ISOLATE_ABORT; } /* Time to isolate some pages for migration */ @@ -369,7 +380,7 @@ static unsigned long isolate_migratepage trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); - return cc->nr_migratepages; + return ISOLATE_SUCCESS; } /* @@ -533,8 +544,15 @@ static int compact_zone(struct zone *zon unsigned long nr_migrate, nr_remaining; int err; - if (!isolate_migratepages(zone, cc)) + switch (isolate_migratepages(zone, cc)) { + case ISOLATE_ABORT: + ret = COMPACT_PARTIAL; + goto out; + case ISOLATE_NONE: continue; + case ISOLATE_SUCCESS: + ; + } nr_migrate = cc->nr_migratepages; err = migrate_pages(&cc->migratepages, compaction_alloc, @@ -558,6 +576,7 @@ static int compact_zone(struct zone *zon } +out: /* Release free pages and check accounting */ cc->nr_freepages -= release_freepages(&cc->freepages); VM_BUG_ON(cc->nr_freepages != 0);