From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 164896B0032 for ; Tue, 13 Jan 2015 05:04:17 -0500 (EST) Received: by mail-wi0-f175.google.com with SMTP id l15so20076511wiw.2 for ; Tue, 13 Jan 2015 02:04:16 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r15si19132714wij.73.2015.01.13.02.04.15 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 13 Jan 2015 02:04:16 -0800 (PST) Message-ID: <54B4ED9D.8050109@suse.cz> Date: Tue, 13 Jan 2015 11:04:13 +0100 From: Vlastimil Babka MIME-Version: 1.0 Subject: Re: [patch 4/6] mm: fix invalid use of pfn_valid_within in test_pages_in_a_zone References: <548f68bb.wuNDZDL8qk6xEWTm%akpm@linux-foundation.org> In-Reply-To: <548f68bb.wuNDZDL8qk6xEWTm%akpm@linux-foundation.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, linux-mm@kvack.org, jcuster@sgi.com, isimatu.yasuaki@jp.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com, rja@sgi.com, stable@vger.kernel.org On 12/16/2014 12:03 AM, akpm@linux-foundation.org wrote: > From: James Custer > Subject: mm: fix invalid use of pfn_valid_within in test_pages_in_a_zone > > 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. It would still be useful to show the BUG, and provide /proc/zoneinfo for us to see where are the corner cases. > 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 > Cc: KAMEZAWA Hiroyuki > Cc: Russ Anderson > Cc: > Signed-off-by: Andrew Morton > --- > > mm/memory_hotplug.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff -puN mm/memory_hotplug.c~mm-fix-invalid-use-of-pfn_valid_within-in-test_pages_in_a_zone mm/memory_hotplug.c > --- a/mm/memory_hotplug.c~mm-fix-invalid-use-of-pfn_valid_within-in-test_pages_in_a_zone > +++ a/mm/memory_hotplug.c > @@ -1331,7 +1331,7 @@ int is_mem_section_removable(unsigned lo > } > > /* > - * 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 s > 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 (i == MAX_ORDER_NR_PAGES) > continue; > page = pfn_to_page(pfn + i); > _ > > -- > 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 > -- 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