From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763336AbZGAAqO (ORCPT ); Tue, 30 Jun 2009 20:46:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761122AbZGAAdZ (ORCPT ); Tue, 30 Jun 2009 20:33:25 -0400 Received: from kroah.org ([198.145.64.141]:59926 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761072AbZGAAdX (ORCPT ); Tue, 30 Jun 2009 20:33:23 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Tue Jun 30 17:15:54 2009 Message-Id: <20090701001553.976012658@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Tue, 30 Jun 2009 17:14:28 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Dimitri Sivanich , Christoph Lameter , Nick Piggin , Mel Gorman Subject: [patch 32/35] mm: fix handling of pagesets for downed cpus References: <20090701001356.007288418@mini.kroah.org> Content-Disposition: inline; filename=mm-fix-handling-of-pagesets-for-downed-cpus.patch In-Reply-To: <20090701002825.GA6518@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.29-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dimitri Sivanich commit 364df0ebfbbb1330bfc6ca159f4d6020efc15a12 upstream. After downing/upping a cpu, an attempt to set /proc/sys/vm/percpu_pagelist_fraction results in an oops in percpu_pagelist_fraction_sysctl_handler(). If a processor is downed then we need to set the pageset pointer back to the boot pageset. Updates of the high water marks should not access pagesets of unpopulated zones (those pointer go to the boot pagesets which would be no longer functional if their size would be increased beyond zero). Signed-off-by: Dimitri Sivanich Signed-off-by: Christoph Lameter Reviewed-by: KOSAKI Motohiro Cc: Nick Piggin Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2804,7 +2804,7 @@ bad: if (dzone == zone) break; kfree(zone_pcp(dzone, cpu)); - zone_pcp(dzone, cpu) = NULL; + zone_pcp(dzone, cpu) = &boot_pageset[cpu]; } return -ENOMEM; } @@ -2819,7 +2819,7 @@ static inline void free_zone_pagesets(in /* Free per_cpu_pageset if it is slab allocated */ if (pset != &boot_pageset[cpu]) kfree(pset); - zone_pcp(zone, cpu) = NULL; + zone_pcp(zone, cpu) = &boot_pageset[cpu]; } } @@ -4494,6 +4494,8 @@ int percpu_pagelist_fraction_sysctl_hand if (!write || (ret == -EINVAL)) return ret; for_each_zone(zone) { + if (!populated_zone(zone)) + continue; for_each_online_cpu(cpu) { unsigned long high; high = zone->present_pages / percpu_pagelist_fraction;