Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752379AbaLJACH (ORCPT ); Tue, 9 Dec 2014 19:02:07 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:57198 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751589AbaLJACF (ORCPT ); Tue, 9 Dec 2014 19:02:05 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.0.1 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20120718-3 Message-ID: <54878D56.4030508@jp.fujitsu.com> Date: Wed, 10 Dec 2014 09:01:26 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: James Custer , , , , CC: , Subject: Re: [PATCH] mm: fix invalid use of pfn_valid_within in test_pages_in_a_zone References: <1418153696-167580-1-git-send-email-jcuster@sgi.com> In-Reply-To: <1418153696-167580-1-git-send-email-jcuster@sgi.com> Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit X-SecurityPolicyCheck-GC: OK by FENCE-Mail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/12/10 4:34), James Custer wrote: > Offlining memory by 'echo 0 > /sys/devices/system/memory/memory#/online' > or reading valid_zones 'cat /sys/devices/system/memory/memory#/valid_zones' > causes BUG: unable to handle kernel paging request due to invalid use of > pfn_valid_within. This is due to a bug in test_pages_in_a_zone. The information is not enough to understand what happened on your system. Could you show full BUG messages? > > In order to use pfn_valid_within within a MAX_ORDER_NR_PAGES block of pages, > a valid pfn within the block must first be found. There only needs to be > one valid pfn found in test_pages_in_a_zone in the first place. So the > fix is to replace pfn_valid_within with pfn_valid such that the first > valid pfn within the pageblock is found (if it exists). This works > independently of CONFIG_HOLES_IN_ZONE. > > Signed-off-by: James Custer > --- > mm/memory_hotplug.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 1bf4807..304c187 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1331,7 +1331,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) > } > > /* > - * Confirm all pages in a range [start, end) is belongs to the same zone. > + * Confirm all pages in a range [start, end) belong to the same zone. > */ > int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) > { > @@ -1342,10 +1342,11 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) > for (pfn = start_pfn; > pfn < end_pfn; > pfn += MAX_ORDER_NR_PAGES) { > - i = 0; > - /* This is just a CONFIG_HOLES_IN_ZONE check.*/ > - while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) > - i++; > + /* Find the first valid pfn in this pageblock */ > + for (i = 0; i < MAX_ORDER_NR_PAGES; i++) { > + if (pfn_valid(pfn + i)) > + break; > + } If CONFIG_HOLES_IN_NODE is set, there is no difference. Am I making a mistake? Thanks, Yasuaki Ishimatsu > if (i == MAX_ORDER_NR_PAGES) > continue; > page = pfn_to_page(pfn + i); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/