From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852AbYGCQpk (ORCPT ); Thu, 3 Jul 2008 12:45:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752018AbYGCQpc (ORCPT ); Thu, 3 Jul 2008 12:45:32 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:50943 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751714AbYGCQpb (ORCPT ); Thu, 3 Jul 2008 12:45:31 -0400 Date: Thu, 3 Jul 2008 09:44:27 -0700 (PDT) From: Linus Torvalds To: Mel Gorman cc: Christoph Lameter , Dan Williams , Andy Whitcroft , linux-mm@kvack.org, linux-kernel@vger.kernel.org, NeilBrown , babydr@baby-dragons.com, lee.schermerhorn@hp.com, a.beregalov@gmail.com, akpm@linux-foundation.org Subject: Re: [PATCH] Do not clobber pgdat->nr_zones during memory initialisation In-Reply-To: <20080703163638.GC18055@csn.ul.ie> Message-ID: References: <20080701175855.GI32727@shadowen.org> <20080701190741.GB16501@csn.ul.ie> <1214944175.26855.18.camel@dwillia2-linux.ch.intel.com> <20080702051759.GA26338@csn.ul.ie> <1215049766.2840.43.camel@dwillia2-linux.ch.intel.com> <20080703042750.GB14614@csn.ul.ie> <20080703050036.GD14614@csn.ul.ie> <1215064455.15797.4.camel@dwillia2-linux.ch.intel.com> <486CD623.8030906@linux-foundation.org> <20080703163638.GC18055@csn.ul.ie> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 3 Jul 2008, Mel Gorman wrote: > > Subject: [PATCH] Do not clobber pgdat->nr_zones during memory initialisation Heh. I already applied it as ObviouslyCorrect(tm), but did the simplification I already pointed out (and which your second version already had) and rewrote your commit message a bit. So it's now committed as follows.. Linus --- commit 494de90098784b8e2797598cefdd34188884ec2e Author: Mel Gorman Date: Thu Jul 3 05:27:51 2008 +0100 Do not overwrite nr_zones on !NUMA when initialising zlcache_ptr The non-NUMA case of build_zonelist_cache() would initialize the zlcache_ptr for both node_zonelists[] to NULL. Which is problematic, since non-NUMA only has a single node_zonelists[] entry, and trying to zero the non-existent second one just overwrote the nr_zones field instead. As kswapd uses this value to determine what reclaim work is necessary, the result is that kswapd never reclaims. This causes processes to stall frequently in low-memory situations as they always direct reclaim. This patch initialises zlcache_ptr correctly. Signed-off-by: Mel Gorman Tested-by: Dan Williams [ Simplified patch a bit ] Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2f55295..f32fae3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2328,7 +2328,6 @@ static void build_zonelists(pg_data_t *pgdat) static void build_zonelist_cache(pg_data_t *pgdat) { pgdat->node_zonelists[0].zlcache_ptr = NULL; - pgdat->node_zonelists[1].zlcache_ptr = NULL; } #endif /* CONFIG_NUMA */