Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753817Ab0GIBQh (ORCPT ); Thu, 8 Jul 2010 21:16:37 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:37134 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751281Ab0GIBQg convert rfc822-to-8bit (ORCPT ); Thu, 8 Jul 2010 21:16:36 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Andrew Morton Subject: Re: [PATCH v2 1/2] vmscan: don't subtraction of unsined Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm , Mel Gorman , Rik van Riel , Minchan Kim , Johannes Weiner In-Reply-To: <20100708130048.fccfcdad.akpm@linux-foundation.org> References: <20100708163401.CD34.A69D9226@jp.fujitsu.com> <20100708130048.fccfcdad.akpm@linux-foundation.org> Message-Id: <20100709090956.CD51.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 8BIT X-Mailer: Becky! ver. 2.50.07 [ja] Date: Fri, 9 Jul 2010 10:16:33 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3498 Lines: 104 > > @@ -2628,16 +2628,16 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) > > * take a long time. > > */ > > while (shrink_slab(sc.nr_scanned, gfp_mask, order) && > > - zone_page_state(zone, NR_SLAB_RECLAIMABLE) > > > - slab_reclaimable - nr_pages) > > + (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages > n)) > > ; > > > > /* > > * Update nr_reclaimed by the number of slab pages we > > * reclaimed from this zone. > > */ > > - sc.nr_reclaimed += slab_reclaimable - > > - zone_page_state(zone, NR_SLAB_RECLAIMABLE); > > + m = zone_page_state(zone, NR_SLAB_RECLAIMABLE); > > + if (m < n) > > + sc.nr_reclaimed += n - m; > > And it's not a completly trivial objection. Your patch made the above > code snippet quite a lot harder to read (and hence harder to maintain). Initially, I proposed following patch to Christoph. but he prefer n and m. To be honest, I don't think this naming is big matter. so you prefer following I'll submit it. ===================================================================== >From 397199d69860061eaa5e1aaadac45c46c76b0522 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Wed, 30 Jun 2010 13:35:16 +0900 Subject: [PATCH] vmscan: don't subtraction of unsined 'slab_reclaimable' and 'nr_pages' are unsigned. so, subtraction is unsafe. Signed-off-by: KOSAKI Motohiro --- mm/vmscan.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9c7e57c..79ff877 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2588,7 +2588,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) .swappiness = vm_swappiness, .order = order, }; - unsigned long slab_reclaimable; + unsigned long nr_slab_pages0, nr_slab_pages1; disable_swap_token(); cond_resched(); @@ -2615,8 +2615,8 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) } while (priority >= 0 && sc.nr_reclaimed < nr_pages); } - slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); - if (slab_reclaimable > zone->min_slab_pages) { + nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); + if (nr_slab_pages0 > zone->min_slab_pages) { /* * shrink_slab() does not currently allow us to determine how * many pages were freed in this zone. So we take the current @@ -2628,16 +2628,17 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) * take a long time. */ while (shrink_slab(sc.nr_scanned, gfp_mask, order) && - zone_page_state(zone, NR_SLAB_RECLAIMABLE) > - slab_reclaimable - nr_pages) + (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages > + nr_slab_pages0)) ; /* * Update nr_reclaimed by the number of slab pages we * reclaimed from this zone. */ - sc.nr_reclaimed += slab_reclaimable - - zone_page_state(zone, NR_SLAB_RECLAIMABLE); + nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); + if (nr_slab_pages1 < nr_slab_pages0) + sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; } p->reclaim_state = NULL; -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/