From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP
Date: Wed, 18 May 2016 09:49:28 +0100 [thread overview]
Message-ID: <20160518084928.GA2527@techsingularity.net> (raw)
In-Reply-To: <573C1F1E.4040201@suse.cz>
On Wed, May 18, 2016 at 09:51:58AM +0200, Vlastimil Babka wrote:
> On 05/17/2016 08:41 AM, Naoya Horiguchi wrote:
> >> @@ -2579,20 +2612,22 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
> >> struct list_head *list;
> >>
> >> local_irq_save(flags);
> >> - pcp = &this_cpu_ptr(zone->pageset)->pcp;
> >> - list = &pcp->lists[migratetype];
> >> - if (list_empty(list)) {
> >> - pcp->count += rmqueue_bulk(zone, 0,
> >> - pcp->batch, list,
> >> - migratetype, cold);
> >> - if (unlikely(list_empty(list)))
> >> - goto failed;
> >> - }
> >> + do {
> >> + pcp = &this_cpu_ptr(zone->pageset)->pcp;
> >> + list = &pcp->lists[migratetype];
> >> + if (list_empty(list)) {
> >> + pcp->count += rmqueue_bulk(zone, 0,
> >> + pcp->batch, list,
> >> + migratetype, cold);
> >> + if (unlikely(list_empty(list)))
> >> + goto failed;
> >> + }
> >>
> >> - if (cold)
> >> - page = list_last_entry(list, struct page, lru);
> >> - else
> >> - page = list_first_entry(list, struct page, lru);
> >> + if (cold)
> >> + page = list_last_entry(list, struct page, lru);
> >> + else
> >> + page = list_first_entry(list, struct page, lru);
> >> + } while (page && check_new_pcp(page));
> >
> > This causes infinite loop when check_new_pcp() returns 1, because the bad
> > page is still in the list (I assume that a bad page never disappears).
> > The original kernel is free from this problem because we do retry after
> > list_del(). So moving the following 3 lines into this do-while block solves
> > the problem?
> >
> > __dec_zone_state(zone, NR_ALLOC_BATCH);
> > list_del(&page->lru);
> > pcp->count--;
> >
> > There seems no infinit loop issue in order > 0 block below, because bad pages
> > are deleted from free list in __rmqueue_smallest().
>
> Ooops, thanks for catching this, wish it was sooner...
>
Still not too late fortunately! Thanks Naoya for identifying this and
Vlastimil for fixing it.
> ----8<----
> From f52f5e2a7dd65f2814183d8fd254ace43120b828 Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@suse.cz>
> 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
> Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Mel Gorman <mgorman@techsingularity.net>
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2016-05-18 8:49 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-15 8:58 [PATCH 00/28] Optimise page alloc/free fast paths v3 Mel Gorman
2016-04-15 8:58 ` [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages Mel Gorman
2016-04-25 9:33 ` Vlastimil Babka
2016-04-26 10:33 ` Mel Gorman
2016-04-26 11:20 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 02/28] mm, page_alloc: Use new PageAnonHead helper in the free page fast path Mel Gorman
2016-04-25 9:56 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 03/28] mm, page_alloc: Reduce branches in zone_statistics Mel Gorman
2016-04-25 11:15 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 04/28] mm, page_alloc: Inline zone_statistics Mel Gorman
2016-04-25 11:17 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 05/28] mm, page_alloc: Inline the fast path of the zonelist iterator Mel Gorman
2016-04-25 14:50 ` Vlastimil Babka
2016-04-26 10:30 ` Mel Gorman
2016-04-26 11:05 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 06/28] mm, page_alloc: Use __dec_zone_state for order-0 page allocation Mel Gorman
2016-04-26 11:25 ` Vlastimil Babka
2016-04-15 8:58 ` [PATCH 07/28] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations Mel Gorman
2016-04-26 11:29 ` Vlastimil Babka
2016-04-15 8:59 ` [PATCH 08/28] mm, page_alloc: Convert alloc_flags to unsigned Mel Gorman
2016-04-26 11:31 ` Vlastimil Babka
2016-04-15 8:59 ` [PATCH 09/28] mm, page_alloc: Convert nr_fair_skipped to bool Mel Gorman
2016-04-26 11:37 ` Vlastimil Babka
2016-04-15 8:59 ` [PATCH 10/28] mm, page_alloc: Remove unnecessary local variable in get_page_from_freelist Mel Gorman
2016-04-26 11:38 ` Vlastimil Babka
2016-04-15 8:59 ` [PATCH 11/28] mm, page_alloc: Remove unnecessary initialisation " Mel Gorman
2016-04-26 11:39 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Mel Gorman
2016-04-15 9:07 ` [PATCH 14/28] mm, page_alloc: Simplify last cpupid reset Mel Gorman
2016-04-26 13:30 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 15/28] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman
2016-04-26 13:41 ` Vlastimil Babka
2016-04-26 14:50 ` Mel Gorman
2016-04-26 15:16 ` Vlastimil Babka
2016-04-26 16:29 ` Mel Gorman
2016-04-15 9:07 ` [PATCH 16/28] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath Mel Gorman
2016-04-26 14:13 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 17/28] mm, page_alloc: Check once if a zone has isolated pageblocks Mel Gorman
2016-04-26 14:27 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 18/28] mm, page_alloc: Shorten the page allocator fast path Mel Gorman
2016-04-26 15:23 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 19/28] mm, page_alloc: Reduce cost of fair zone allocation policy retry Mel Gorman
2016-04-26 17:24 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 20/28] mm, page_alloc: Shortcut watermark checks for order-0 pages Mel Gorman
2016-04-26 17:32 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 21/28] mm, page_alloc: Avoid looking up the first zone in a zonelist twice Mel Gorman
2016-04-26 17:46 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 22/28] mm, page_alloc: Remove field from alloc_context Mel Gorman
2016-04-15 9:07 ` [PATCH 23/28] mm, page_alloc: Check multiple page fields with a single branch Mel Gorman
2016-04-26 18:41 ` Vlastimil Babka
2016-04-27 10:07 ` Mel Gorman
2016-04-15 9:07 ` [PATCH 24/28] mm, page_alloc: Remove unnecessary variable from free_pcppages_bulk Mel Gorman
2016-04-26 18:43 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 25/28] mm, page_alloc: Inline pageblock lookup in page free fast paths Mel Gorman
2016-04-26 19:10 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 26/28] cpuset: use static key better and convert to new API Mel Gorman
2016-04-26 19:49 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 27/28] mm, page_alloc: Defer debugging checks of freed pages until a PCP drain Mel Gorman
2016-04-27 11:59 ` Vlastimil Babka
2016-04-27 12:01 ` [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Vlastimil Babka
2016-04-27 12:01 ` [PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check Vlastimil Babka
2016-04-27 12:41 ` Mel Gorman
2016-04-27 13:00 ` Vlastimil Babka
2016-04-27 12:01 ` [PATCH 3/3] mm, page_alloc: don't duplicate code in free_pcp_prepare Vlastimil Babka
2016-04-27 12:37 ` [PATCH 1/3] mm, page_alloc: un-inline the bad part of free_pages_check Mel Gorman
2016-04-27 12:53 ` Vlastimil Babka
2016-04-15 9:07 ` [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Mel Gorman
2016-04-27 14:06 ` Vlastimil Babka
2016-04-27 15:31 ` Mel Gorman
2016-05-17 6:41 ` Naoya Horiguchi
2016-05-18 7:51 ` Vlastimil Babka
2016-05-18 7:55 ` Vlastimil Babka
2016-05-18 8:49 ` Mel Gorman [this message]
2016-04-26 12:04 ` [PATCH 13/28] mm, page_alloc: Remove redundant check for empty zonelist Vlastimil Babka
2016-04-26 13:00 ` Mel Gorman
2016-04-26 19:11 ` Andrew Morton
2016-04-15 12:44 ` [PATCH 00/28] Optimise page alloc/free fast paths v3 Jesper Dangaard Brouer
2016-04-15 13:08 ` Mel Gorman
2016-04-16 7:21 ` [PATCH 12/28] mm, page_alloc: Remove unnecessary initialisation from __alloc_pages_nodemask() Mel Gorman
2016-04-26 11:41 ` Vlastimil Babka
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