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From: Minchan Kim <minchan@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Heesub Shin <heesub.shin@samsung.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Dongjun Shin <d.j.shin@samsung.com>,
	Sunghwan Yun <sunghwan.yun@samsung.com>,
	Mel Gorman <mgorman@suse.de>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Michal Nazarewicz <mina86@mina86.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 1/2] mm/compaction: make isolate_freepages start at pageblock boundary
Date: Thu, 17 Apr 2014 08:43:09 +0900	[thread overview]
Message-ID: <20140416234309.GE27534@bbox> (raw)
In-Reply-To: <1397553507-15330-1-git-send-email-vbabka@suse.cz>

On Tue, Apr 15, 2014 at 11:18:26AM +0200, Vlastimil Babka wrote:
> The compaction freepage scanner implementation in isolate_freepages() starts
> by taking the current cc->free_pfn value as the first pfn. In a for loop, it
> scans from this first pfn to the end of the pageblock, and then subtracts
> pageblock_nr_pages from the first pfn to obtain the first pfn for the next
> for loop iteration.
> 
> This means that when cc->free_pfn starts at offset X rather than being aligned
> on pageblock boundary, the scanner will start at offset X in all scanned
> pageblock, ignoring potentially many free pages. Currently this can happen when
> a) zone's end pfn is not pageblock aligned, or
> b) through zone->compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled and
>    a hole spanning the beginning of a pageblock
> 
> This patch fixes the problem by aligning the initial pfn in isolate_freepages()
> to pageblock boundary. This also allows to replace the end-of-pageblock
> alignment within the for loop with a simple pageblock_nr_pages increment.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Reported-by: Heesub Shin <heesub.shin@samsung.com>

Acked-by: Minchan Kim <minchan@kernel.org>

-stable stuff?

-- 
Kind regards,
Minchan Kim

WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Heesub Shin <heesub.shin@samsung.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Dongjun Shin <d.j.shin@samsung.com>,
	Sunghwan Yun <sunghwan.yun@samsung.com>,
	Mel Gorman <mgorman@suse.de>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Michal Nazarewicz <mina86@mina86.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 1/2] mm/compaction: make isolate_freepages start at pageblock boundary
Date: Thu, 17 Apr 2014 08:43:09 +0900	[thread overview]
Message-ID: <20140416234309.GE27534@bbox> (raw)
In-Reply-To: <1397553507-15330-1-git-send-email-vbabka@suse.cz>

On Tue, Apr 15, 2014 at 11:18:26AM +0200, Vlastimil Babka wrote:
> The compaction freepage scanner implementation in isolate_freepages() starts
> by taking the current cc->free_pfn value as the first pfn. In a for loop, it
> scans from this first pfn to the end of the pageblock, and then subtracts
> pageblock_nr_pages from the first pfn to obtain the first pfn for the next
> for loop iteration.
> 
> This means that when cc->free_pfn starts at offset X rather than being aligned
> on pageblock boundary, the scanner will start at offset X in all scanned
> pageblock, ignoring potentially many free pages. Currently this can happen when
> a) zone's end pfn is not pageblock aligned, or
> b) through zone->compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled and
>    a hole spanning the beginning of a pageblock
> 
> This patch fixes the problem by aligning the initial pfn in isolate_freepages()
> to pageblock boundary. This also allows to replace the end-of-pageblock
> alignment within the for loop with a simple pageblock_nr_pages increment.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Reported-by: Heesub Shin <heesub.shin@samsung.com>

Acked-by: Minchan Kim <minchan@kernel.org>

-stable stuff?

-- 
Kind regards,
Minchan Kim

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  parent reply	other threads:[~2014-04-16 23:42 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-03  8:57 [PATCH 1/2] mm/compaction: clean up unused code lines Heesub Shin
2014-04-03  8:57 ` Heesub Shin
2014-04-03  8:57 ` [PATCH 2/2] mm/compaction: fix to initialize free scanner properly Heesub Shin
2014-04-03  8:57   ` Heesub Shin
2014-04-07 14:46   ` Vlastimil Babka
2014-04-07 14:46     ` Vlastimil Babka
2014-04-15  9:18     ` [PATCH 1/2] mm/compaction: make isolate_freepages start at pageblock boundary Vlastimil Babka
2014-04-15  9:18       ` Vlastimil Babka
2014-04-15  9:18       ` [PATCH 2/2] mm/compaction: cleanup isolate_freepages() Vlastimil Babka
2014-04-15  9:18         ` Vlastimil Babka
2014-04-16  1:53         ` Joonsoo Kim
2014-04-16  1:53           ` Joonsoo Kim
2014-04-16 15:49         ` Rik van Riel
2014-04-16 15:49           ` Rik van Riel
2014-04-17  0:07         ` Minchan Kim
2014-04-17  0:07           ` Minchan Kim
2014-04-21 19:41           ` Andrew Morton
2014-04-21 19:41             ` Andrew Morton
2014-04-21 21:43             ` Vlastimil Babka
2014-04-21 21:43               ` Vlastimil Babka
2014-04-21 23:53               ` Minchan Kim
2014-04-21 23:53                 ` Minchan Kim
2014-04-22  6:33                 ` Vlastimil Babka
2014-04-22  6:33                   ` Vlastimil Babka
2014-04-22  6:52                   ` Minchan Kim
2014-04-22  6:52                     ` Minchan Kim
2014-04-22 13:17                     ` Vlastimil Babka
2014-04-22 13:17                       ` Vlastimil Babka
2014-04-23  2:58                       ` Joonsoo Kim
2014-04-23  2:58                         ` Joonsoo Kim
2014-04-23  7:30                         ` Vlastimil Babka
2014-04-23  7:30                           ` Vlastimil Babka
2014-04-23 13:54                           ` Joonsoo Kim
2014-04-23 13:54                             ` Joonsoo Kim
2014-04-23 14:31                             ` Vlastimil Babka
2014-04-23 14:31                               ` Vlastimil Babka
2014-04-25  8:29                               ` Joonsoo Kim
2014-04-25  8:29                                 ` Joonsoo Kim
2014-04-29  8:40                                 ` Vlastimil Babka
2014-04-29  8:40                                   ` Vlastimil Babka
2014-05-01  1:58                                 ` Michal Nazarewicz
2014-04-16  1:52       ` [PATCH 1/2] mm/compaction: make isolate_freepages start at pageblock boundary Joonsoo Kim
2014-04-16  1:52         ` Joonsoo Kim
2014-04-16 15:47       ` Rik van Riel
2014-04-16 15:47         ` Rik van Riel
2014-04-16 23:43       ` Minchan Kim [this message]
2014-04-16 23:43         ` Minchan Kim
2014-04-07 14:40 ` [PATCH 1/2] mm/compaction: clean up unused code lines Vlastimil Babka
2014-04-07 14:40   ` Vlastimil Babka

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