From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 17/28] mm, page_alloc: Check once if a zone has isolated pageblocks
Date: Tue, 26 Apr 2016 16:27:36 +0200 [thread overview]
Message-ID: <571F7AD8.10301@suse.cz> (raw)
In-Reply-To: <1460711275-1130-5-git-send-email-mgorman@techsingularity.net>
On 04/15/2016 11:07 AM, Mel Gorman wrote:
> When bulk freeing pages from the per-cpu lists the zone is checked
> for isolated pageblocks on every release. This patch checks it once
> per drain. Technically this is race-prone but so is the existing
> code.
No, existing code is protected by zone->lock. Both checking and manipulating the
variable zone->nr_isolate_pageblock should happen under the lock, as correct
accounting depends on it.
Luckily, the patch could be simply fixed by removing last changelog sentence and:
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 49aabfb39ff1..7de04bdd8c67 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -831,9 +831,10 @@ static void free_pcppages_bulk(struct zone *zone, int count,
int batch_free = 0;
int to_free = count;
unsigned long nr_scanned;
- bool isolated_pageblocks = has_isolate_pageblock(zone);
+ bool isolated_pageblocks;
spin_lock(&zone->lock);
+ isolated_pageblocks = has_isolate_pageblock(zone);
nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
if (nr_scanned)
__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> ---
> mm/page_alloc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 4a364e318873..835a1c434832 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -831,6 +831,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
> int batch_free = 0;
> int to_free = count;
> unsigned long nr_scanned;
> + bool isolated_pageblocks = has_isolate_pageblock(zone);
>
> spin_lock(&zone->lock);
> nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
> @@ -870,7 +871,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
> /* MIGRATE_ISOLATE page should not go to pcplists */
> VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
> /* Pageblock could have been isolated meanwhile */
> - if (unlikely(has_isolate_pageblock(zone)))
> + if (unlikely(isolated_pageblocks))
> mt = get_pageblock_migratetype(page);
>
> __free_one_page(page, page_to_pfn(page), zone, 0, mt);
>
next prev parent reply other threads:[~2016-04-26 14:27 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 [this message]
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
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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