From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725AbcERHzR (ORCPT ); Wed, 18 May 2016 03:55:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:51747 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752686AbcERHzO (ORCPT ); Wed, 18 May 2016 03:55:14 -0400 Subject: Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP To: Naoya Horiguchi , Mel Gorman References: <1460710760-32601-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-16-git-send-email-mgorman@techsingularity.net> <20160517064153.GA23930@hori1.linux.bs1.fc.nec.co.jp> <573C1F1E.4040201@suse.cz> Cc: Andrew Morton , Jesper Dangaard Brouer , Linux-MM , LKML From: Vlastimil Babka Message-ID: <573C1FE0.3010500@suse.cz> Date: Wed, 18 May 2016 09:55:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <573C1F1E.4040201@suse.cz> Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/18/2016 09:51 AM, Vlastimil Babka wrote: > ----8<---- > From f52f5e2a7dd65f2814183d8fd254ace43120b828 Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Wed, 18 May 2016 09:41:01 +0200 > Subject: [PATCH] mm, page_alloc: prevent infinite loop in buffered_rmqueue() > > In DEBUG_VM kernel, we can hit infinite loop for order == 0 in > buffered_rmqueue() when check_new_pcp() returns 1, because the bad page is > never removed from the pcp list. Fix this by removing the page before retrying. > Also we don't need to check if page is non-NULL, because we simply grab it from > the list which was just tested for being non-empty. > > Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch Wrong. Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-pages-allocated-from-the-pcp.patch > Reported-by: Naoya Horiguchi > Signed-off-by: Vlastimil Babka > --- > mm/page_alloc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 8c81e2e7b172..d5b93e5dd697 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2641,11 +2641,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, > page = list_last_entry(list, struct page, lru); > else > page = list_first_entry(list, struct page, lru); > - } while (page && check_new_pcp(page)); > > - __dec_zone_state(zone, NR_ALLOC_BATCH); > - list_del(&page->lru); > - pcp->count--; > + __dec_zone_state(zone, NR_ALLOC_BATCH); > + list_del(&page->lru); > + pcp->count--; > + > + } while (check_new_pcp(page)); > } else { > /* > * We most definitely don't want callers attempting to > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 3B4EC6B007E for ; Wed, 18 May 2016 03:55:14 -0400 (EDT) Received: by mail-wm0-f69.google.com with SMTP id a17so9021480wme.1 for ; Wed, 18 May 2016 00:55:14 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n184si9353576wmn.115.2016.05.18.00.55.13 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 18 May 2016 00:55:13 -0700 (PDT) Subject: Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP References: <1460710760-32601-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-16-git-send-email-mgorman@techsingularity.net> <20160517064153.GA23930@hori1.linux.bs1.fc.nec.co.jp> <573C1F1E.4040201@suse.cz> From: Vlastimil Babka Message-ID: <573C1FE0.3010500@suse.cz> Date: Wed, 18 May 2016 09:55:12 +0200 MIME-Version: 1.0 In-Reply-To: <573C1F1E.4040201@suse.cz> Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi , Mel Gorman Cc: Andrew Morton , Jesper Dangaard Brouer , Linux-MM , LKML On 05/18/2016 09:51 AM, Vlastimil Babka wrote: > ----8<---- > From f52f5e2a7dd65f2814183d8fd254ace43120b828 Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Wed, 18 May 2016 09:41:01 +0200 > Subject: [PATCH] mm, page_alloc: prevent infinite loop in buffered_rmqueue() > > In DEBUG_VM kernel, we can hit infinite loop for order == 0 in > buffered_rmqueue() when check_new_pcp() returns 1, because the bad page is > never removed from the pcp list. Fix this by removing the page before retrying. > Also we don't need to check if page is non-NULL, because we simply grab it from > the list which was just tested for being non-empty. > > Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch Wrong. Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-pages-allocated-from-the-pcp.patch > Reported-by: Naoya Horiguchi > Signed-off-by: Vlastimil Babka > --- > mm/page_alloc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 8c81e2e7b172..d5b93e5dd697 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2641,11 +2641,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, > page = list_last_entry(list, struct page, lru); > else > page = list_first_entry(list, struct page, lru); > - } while (page && check_new_pcp(page)); > > - __dec_zone_state(zone, NR_ALLOC_BATCH); > - list_del(&page->lru); > - pcp->count--; > + __dec_zone_state(zone, NR_ALLOC_BATCH); > + list_del(&page->lru); > + pcp->count--; > + > + } while (check_new_pcp(page)); > } else { > /* > * We most definitely don't want callers attempting to > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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