Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933350AbcJLNB5 (ORCPT ); Wed, 12 Oct 2016 09:01:57 -0400 Received: from mail.kernel.org ([198.145.29.136]:48062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932658AbcJLMoZ (ORCPT ); Wed, 12 Oct 2016 08:44:25 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Banman , Russ Anderson , Alex Thorlton , Yinghai Lu , Greg KH , Seth Jennings , Andrew Morton , Linus Torvalds , Zefan Li Subject: [PATCH 3.4 108/125] mm/memory_hotplug.c: check for missing sections in test_pages_in_a_zone() Date: Wed, 12 Oct 2016 20:33:44 +0800 Message-Id: <1476275641-4697-108-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1476275600-4626-1-git-send-email-lizf@kernel.org> References: <1476275600-4626-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2974 Lines: 86 From: Andrew Banman 3.4.113-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 5f0f2887f4de9508dcf438deab28f1de8070c271 upstream. test_pages_in_a_zone() does not account for the possibility of missing sections in the given pfn range. pfn_valid_within always returns 1 when CONFIG_HOLES_IN_ZONE is not set, allowing invalid pfns from missing sections to pass the test, leading to a kernel oops. Wrap an additional pfn loop with PAGES_PER_SECTION granularity to check for missing sections before proceeding into the zone-check code. This also prevents a crash from offlining memory devices with missing sections. Despite this, it may be a good idea to keep the related patch '[PATCH 3/3] drivers: memory: prohibit offlining of memory blocks with missing sections' because missing sections in a memory block may lead to other problems not covered by the scope of this fix. Signed-off-by: Andrew Banman Acked-by: Alex Thorlton Cc: Russ Anderson Cc: Alex Thorlton Cc: Yinghai Lu Cc: Greg KH Cc: Seth Jennings Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Zefan Li --- mm/memory_hotplug.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 09d87b7..223232a 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -716,23 +716,30 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) */ static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) { - unsigned long pfn; + unsigned long pfn, sec_end_pfn; struct zone *zone = NULL; struct page *page; int i; - for (pfn = start_pfn; + for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(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++; - if (i == MAX_ORDER_NR_PAGES) + pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) { + /* Make sure the memory section is present first */ + if (!present_section_nr(pfn_to_section_nr(pfn))) continue; - page = pfn_to_page(pfn + i); - if (zone && page_zone(page) != zone) - return 0; - zone = page_zone(page); + for (; pfn < sec_end_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++; + if (i == MAX_ORDER_NR_PAGES) + continue; + page = pfn_to_page(pfn + i); + if (zone && page_zone(page) != zone) + return 0; + zone = page_zone(page); + } } return 1; } -- 1.9.1