From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 3 Jul 2008 18:16:10 +0100 From: Mel Gorman Subject: Re: [PATCH] Do not clobber pgdat->nr_zones during memory initialisation Message-ID: <20080703171610.GG18055@csn.ul.ie> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds 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 List-ID: On (03/07/08 09:44), Linus Torvalds didst pronounce: > > > 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.. > Perfect. The log even looks like it was written by a sane person. Thanks for that. > 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 */ > -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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