Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751735AbcDTTrn (ORCPT ); Wed, 20 Apr 2016 15:47:43 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:35543 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902AbcDTTrk (ORCPT ); Wed, 20 Apr 2016 15:47:40 -0400 From: Michal Hocko To: Andrew Morton Cc: Linus Torvalds , Johannes Weiner , Mel Gorman , David Rientjes , Tetsuo Handa , Joonsoo Kim , Hillf Danton , Vlastimil Babka , , LKML , Michal Hocko Subject: [PATCH 01/14] vmscan: consider classzone_idx in compaction_ready Date: Wed, 20 Apr 2016 15:47:14 -0400 Message-Id: <1461181647-8039-2-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1461181647-8039-1-git-send-email-mhocko@kernel.org> References: <1461181647-8039-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3371 Lines: 73 From: Michal Hocko while playing with the oom detection rework [1] I have noticed that my heavy order-9 (hugetlb) load close to OOM ended up in an endless loop where the reclaim hasn't made any progress but did_some_progress didn't reflect that and compaction_suitable was backing off because no zone is above low wmark + 1 << order. It turned out that this is in fact an old standing bug in compaction_ready which ignores the requested_highidx and did the watermark check for 0 classzone_idx. This succeeds for zone DMA most of the time as the zone is mostly unused because of lowmem protection. This also means that the OOM killer wouldn't be triggered for higher order requests even when there is no reclaim progress and we essentially rely on order-0 request to find this out. This has been broken in one way or another since fe4b1b244bdb ("mm: vmscan: when reclaiming for compaction, ensure there are sufficient free pages available") but only since 7335084d446b ("mm: vmscan: do not OOM if aborting reclaim to start compaction") we are not invoking the OOM killer based on the wrong calculation. Propagate requested_highidx down to compaction_ready and use it for both the watermak check and compaction_suitable to fix this issue. [1] http://lkml.kernel.org/r/1459855533-4600-1-git-send-email-mhocko@kernel.org Acked-by: Vlastimil Babka Signed-off-by: Michal Hocko --- mm/vmscan.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index c839adc13efd..3e6347e2a5fc 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2482,7 +2482,7 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc, * Returns true if compaction should go ahead for a high-order request, or * the high-order allocation would succeed without compaction. */ -static inline bool compaction_ready(struct zone *zone, int order) +static inline bool compaction_ready(struct zone *zone, int order, int classzone_idx) { unsigned long balance_gap, watermark; bool watermark_ok; @@ -2496,7 +2496,7 @@ static inline bool compaction_ready(struct zone *zone, int order) balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP( zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO)); watermark = high_wmark_pages(zone) + balance_gap + (2UL << order); - watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0); + watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, classzone_idx); /* * If compaction is deferred, reclaim up to a point where @@ -2509,7 +2509,7 @@ static inline bool compaction_ready(struct zone *zone, int order) * If compaction is not ready to start and allocation is not likely * to succeed without it, then keep reclaiming. */ - if (compaction_suitable(zone, order, 0, 0) == COMPACT_SKIPPED) + if (compaction_suitable(zone, order, 0, classzone_idx) == COMPACT_SKIPPED) return false; return watermark_ok; @@ -2589,7 +2589,7 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && zonelist_zone_idx(z) <= requested_highidx && - compaction_ready(zone, sc->order)) { + compaction_ready(zone, sc->order, requested_highidx)) { sc->compaction_ready = true; continue; } -- 2.8.0.rc3