From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35270 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbdADKHJ (ORCPT ); Wed, 4 Jan 2017 05:07:09 -0500 Subject: Patch "mm, page_alloc: keep pcp count and list contents in sync if struct page is corrupted" has been added to the 4.8-stable tree To: mgorman@techsingularity.net, akpm@linux-foundation.org, brouer@redhat.com, cl@linux.com, gregkh@linuxfoundation.org, hannes@cmpxchg.org, hillf.zj@alibaba-inc.com, iamjoonsoo.kim@lge.com, mgorman@suse.de, mhocko@suse.com, torvalds@linux-foundation.org, vbabka@suse.cz Cc: , From: Date: Wed, 04 Jan 2017 11:07:05 +0100 Message-ID: <148352442517940@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled mm, page_alloc: keep pcp count and list contents in sync if struct page is corrupted to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-page_alloc-keep-pcp-count-and-list-contents-in-sync-if-struct-page-is-corrupted.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From a6de734bc002fe2027ccc074fbbd87d72957b7a4 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 12 Dec 2016 16:44:41 -0800 Subject: mm, page_alloc: keep pcp count and list contents in sync if struct page is corrupted From: Mel Gorman commit a6de734bc002fe2027ccc074fbbd87d72957b7a4 upstream. Vlastimil Babka pointed out that commit 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") will allow the per-cpu list counter to be out of sync with the per-cpu list contents if a struct page is corrupted. The consequence is an infinite loop if the per-cpu lists get fully drained by free_pcppages_bulk because all the lists are empty but the count is positive. The infinite loop occurs here do { batch_free++; if (++migratetype == MIGRATE_PCPTYPES) migratetype = 0; list = &pcp->lists[migratetype]; } while (list_empty(list)); What the user sees is a bad page warning followed by a soft lockup with interrupts disabled in free_pcppages_bulk(). This patch keeps the accounting in sync. Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") Link: http://lkml.kernel.org/r/20161202112951.23346-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Acked-by: Michal Hocko Acked-by: Hillf Danton Cc: Christoph Lameter Cc: Johannes Weiner Cc: Jesper Dangaard Brouer Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2173,7 +2173,7 @@ static int rmqueue_bulk(struct zone *zon unsigned long count, struct list_head *list, int migratetype, bool cold) { - int i; + int i, alloced = 0; spin_lock(&zone->lock); for (i = 0; i < count; ++i) { @@ -2198,13 +2198,21 @@ static int rmqueue_bulk(struct zone *zon else list_add_tail(&page->lru, list); list = &page->lru; + alloced++; if (is_migrate_cma(get_pcppage_migratetype(page))) __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, -(1 << order)); } + + /* + * i pages were removed from the buddy list even if some leak due + * to check_pcp_refill failing so adjust NR_FREE_PAGES based + * on i. Do not confuse with 'alloced' which is the number of + * pages added to the pcp list. + */ __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order)); spin_unlock(&zone->lock); - return i; + return alloced; } #ifdef CONFIG_NUMA Patches currently in stable-queue which might be from mgorman@techsingularity.net are queue-4.8/mm-page_alloc-keep-pcp-count-and-list-contents-in-sync-if-struct-page-is-corrupted.patch