From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755896Ab2GaFGi (ORCPT ); Tue, 31 Jul 2012 01:06:38 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:48513 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753190Ab2GaEuE (ORCPT ); Tue, 31 Jul 2012 00:50:04 -0400 Message-Id: <20120731044312.684965795@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Tue, 31 Jul 2012 05:43:19 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mel Gorman , Rik van Riel , Andrea Arcangeli , Minchan Kim , Dave Jones , Jan Kara , Andy Isaacson , Nai Xia , Johannes Weiner Subject: [ 09/73] mm: vmscan: check if reclaim should really abort even if compaction_ready() is true for one zone In-Reply-To: <20120731044310.013763753@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mel Gorman commit 0cee34fd72c582b4f8ad8ce00645b75fb4168199 upstream. Stable note: Not tracked on Bugzilla. THP and compaction was found to aggressively reclaim pages and stall systems under different situations that was addressed piecemeal over time. If compaction can proceed for a given zone, shrink_zones() does not reclaim any more pages from it. After commit [e0c2327: vmscan: abort reclaim/compaction if compaction can proceed], do_try_to_free_pages() tries to finish as soon as possible once one zone can compact. This was intended to prevent slabs being shrunk unnecessarily but there are side-effects. One is that a small zone that is ready for compaction will abort reclaim even if the chances of successfully allocating a THP from that zone is small. It also means that reclaim can return too early even though sc->nr_to_reclaim pages were not reclaimed. This partially reverts the commit until it is proven that slabs are really being shrunk unnecessarily but preserves the check to return 1 to avoid OOM if reclaim was aborted prematurely. [aarcange@redhat.com: This patch replaces a revert from Andrea] Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- mm/vmscan.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2173,7 +2173,8 @@ static inline bool compaction_ready(stru * * This function returns true if a zone is being reclaimed for a costly * high-order allocation and compaction is ready to begin. This indicates to - * the caller that it should retry the allocation or fail. + * the caller that it should consider retrying the allocation instead of + * further reclaim. */ static bool shrink_zones(int priority, struct zonelist *zonelist, struct scan_control *sc) @@ -2182,7 +2183,7 @@ static bool shrink_zones(int priority, s struct zone *zone; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; - bool should_abort_reclaim = false; + bool aborted_reclaim = false; for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(sc->gfp_mask), sc->nodemask) { @@ -2208,7 +2209,7 @@ static bool shrink_zones(int priority, s * allocations. */ if (compaction_ready(zone, sc)) { - should_abort_reclaim = true; + aborted_reclaim = true; continue; } } @@ -2230,7 +2231,7 @@ static bool shrink_zones(int priority, s shrink_zone(priority, zone, sc); } - return should_abort_reclaim; + return aborted_reclaim; } static bool zone_reclaimable(struct zone *zone) @@ -2284,7 +2285,7 @@ static unsigned long do_try_to_free_page struct zoneref *z; struct zone *zone; unsigned long writeback_threshold; - bool should_abort_reclaim; + bool aborted_reclaim; get_mems_allowed(); delayacct_freepages_start(); @@ -2296,9 +2297,7 @@ static unsigned long do_try_to_free_page sc->nr_scanned = 0; if (!priority) disable_swap_token(sc->mem_cgroup); - should_abort_reclaim = shrink_zones(priority, zonelist, sc); - if (should_abort_reclaim) - break; + aborted_reclaim = shrink_zones(priority, zonelist, sc); /* * Don't shrink slabs when reclaiming memory from @@ -2365,8 +2364,8 @@ out: if (oom_killer_disabled) return 0; - /* Aborting reclaim to try compaction? don't OOM, then */ - if (should_abort_reclaim) + /* Aborted reclaim to try compaction? don't OOM, then */ + if (aborted_reclaim) return 1; /* top priority shrink_zones still had more to do? don't OOM, then */