From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 242486B00D3 for ; Tue, 9 Mar 2010 15:33:30 -0500 (EST) Date: Tue, 9 Mar 2010 14:33:19 -0600 (CST) From: Christoph Lameter Subject: Re: mm: Do not iterate over NR_CPUS in __zone_pcp_update() In-Reply-To: <20100309122253.3f3d4a53.akpm@linux-foundation.org> Message-ID: References: <20100309122253.3f3d4a53.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Thomas Gleixner , LKML , linux-mm@kvack.org, Pekka Enberg List-ID: On Tue, 9 Mar 2010, Andrew Morton wrote: > > __zone_pcp_update() iterates over NR_CPUS instead of limiting the > > access to the possible cpus. This might result in access to > > uninitialized areas as the per cpu allocator only populates the per > > cpu memory for possible cpus. > > > > Signed-off-by: Thomas Gleixner > > --- > > mm/page_alloc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > Index: linux-2.6/mm/page_alloc.c > > =================================================================== > > --- linux-2.6.orig/mm/page_alloc.c > > +++ linux-2.6/mm/page_alloc.c > > @@ -3224,7 +3224,7 @@ static int __zone_pcp_update(void *data) > > int cpu; > > unsigned long batch = zone_batchsize(zone), flags; > > > > - for (cpu = 0; cpu < NR_CPUS; cpu++) { > > + for_each_possible_cpu(cpu) { > > struct per_cpu_pageset *pset; > > struct per_cpu_pages *pcp; > > > > I'm having trouble working out whether we want to backport this into > 2.6.33.x or earlier. Help? Nope. This problem was created as a result of the dynamic allocation of pagesets from percpu memory that went in during the merge window. (99dcc3e5a94ed491fbef402831d8c0bbb267f995) -- 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