From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f54.google.com (mail-la0-f54.google.com [209.85.215.54]) by kanga.kvack.org (Postfix) with ESMTP id D4AEA6B0036 for ; Fri, 5 Sep 2014 06:14:56 -0400 (EDT) Received: by mail-la0-f54.google.com with SMTP id b17so13742206lan.27 for ; Fri, 05 Sep 2014 03:14:56 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id a12si2160275lbl.110.2014.09.05.03.14.54 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 05 Sep 2014 03:14:55 -0700 (PDT) Date: Fri, 5 Sep 2014 11:14:51 +0100 From: Mel Gorman Subject: [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP Message-ID: <20140905101451.GF17501@suse.de> References: <1404893588-21371-1-git-send-email-mgorman@suse.de> <1404893588-21371-7-git-send-email-mgorman@suse.de> <53E4EC53.1050904@suse.cz> <20140811121241.GD7970@suse.de> <53E8B83D.1070004@suse.cz> <20140902140116.GD29501@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20140902140116.GD29501@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vlastimil Babka , Johannes Weiner , Linux Kernel , Linux-MM , Linux-FSDevel Commit 4ffeaf35 (mm: page_alloc: reduce cost of the fair zone allocation policy) broke the fair zone allocation policy on UP with these hunks. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6e5e8f7..fb99081 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1612,6 +1612,9 @@ again: } __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order)); + if (zone_page_state(zone, NR_ALLOC_BATCH) == 0 && + !zone_is_fair_depleted(zone)) + zone_set_flag(zone, ZONE_FAIR_DEPLETED); __count_zone_vm_events(PGALLOC, zone, 1 << order); zone_statistics(preferred_zone, zone, gfp_flags); @@ -1966,8 +1985,10 @@ zonelist_scan: if (alloc_flags & ALLOC_FAIR) { if (!zone_local(preferred_zone, zone)) break; - if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0) + if (zone_is_fair_depleted(zone)) { + nr_fair_skipped++; continue; + } } The problem is that a <= check was replaced with a ==. On SMP it doesn't matter because negative values are returned as zero due to per-CPU drift which is not possible in the UP case. Vlastimil Babka correctly pointed out that this can be negative due to high-order allocations. This patch fixes the problem. Reported-by: Vlastimil Babka Signed-off-by: Mel Gorman --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 18cee0d..cd4c05c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1612,7 +1612,7 @@ again: } __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order)); - if (zone_page_state(zone, NR_ALLOC_BATCH) == 0 && + if (zone_page_state(zone, NR_ALLOC_BATCH) <= 0 && !zone_is_fair_depleted(zone)) zone_set_flag(zone, ZONE_FAIR_DEPLETED); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org