Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759389AbcLBJiH (ORCPT ); Fri, 2 Dec 2016 04:38:07 -0500 Received: from out0-129.mail.aliyun.com ([140.205.0.129]:44056 "EHLO out0-129.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757816AbcLBJhv (ORCPT ); Fri, 2 Dec 2016 04:37:51 -0500 X-Greylist: delayed 398 seconds by postgrey-1.27 at vger.kernel.org; Fri, 02 Dec 2016 04:37:48 EST X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R211e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03290;MF=hillf.zj@alibaba-inc.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---.7FNw0.j_1480671007; Reply-To: "Hillf Danton" From: "Hillf Danton" To: "'Vlastimil Babka'" , "'Mel Gorman'" , "'Andrew Morton'" Cc: "'Christoph Lameter'" , "'Michal Hocko'" , "'Johannes Weiner'" , "'Jesper Dangaard Brouer'" , "'Linux-MM'" , "'Linux-Kernel'" References: <20161202002244.18453-1-mgorman@techsingularity.net> <20161202002244.18453-2-mgorman@techsingularity.net> <01d601d24c4e$dca6e190$95f4a4b0$@alibaba-inc.com> <55e1d640-72cf-d7b5-695b-87863ca7a843@suse.cz> In-Reply-To: <55e1d640-72cf-d7b5-695b-87863ca7a843@suse.cz> Subject: Re: [PATCH 1/2] mm, page_alloc: Keep pcp count and list contents in sync if struct page is corrupted Date: Fri, 02 Dec 2016 17:30:07 +0800 Message-ID: <01f201d24c7e$ac04ed40$040ec7c0$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQIHR4g+bvnVwkChnMB02ZSKZ5j4cAFySElFA3NVdKYCmZj0hKBOcO+g Content-Language: zh-cn Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1954 Lines: 53 On Friday, December 02, 2016 2:19 PM Vlastimil Babka wrote: > On 12/02/2016 04:47 AM, Hillf Danton wrote: > > On Friday, December 02, 2016 8:23 AM Mel Gorman wrote: > >> 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. This patch keeps the accounting in sync. > >> > >> Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") > >> Signed-off-by: Mel Gorman > >> cc: stable@vger.kernel.org [4.7+] > > Acked-by: Vlastimil Babka > > >> --- > >> mm/page_alloc.c | 5 +++-- > >> 1 file changed, 3 insertions(+), 2 deletions(-) > >> > >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >> index 6de9440e3ae2..777ed59570df 100644 > >> --- a/mm/page_alloc.c > >> +++ b/mm/page_alloc.c > >> @@ -2192,7 +2192,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, > >> 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) { > >> @@ -2217,13 +2217,14 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, > >> 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)); > >> } > >> __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order)); > > > > Now i is a pure index, yes? > > No, even if a page fails the check_pcp_refill() check and is not > "allocated", it is also no longer a free page, so it's correct to > subtract it from NR_FREE_PAGES. > Yes, we can allocate free page next time. thanks Hillf