Re: + mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch added to -mm tree

[Joonsoo Kim]

On Tue, Oct 14, 2014 at 01:53:44PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> 
> The patch titled
>      Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range
> has been added to the -mm tree.  Its filename is
>      mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> 
> This patch should soon appear at
>     http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> and later at
>     http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-premature-range-skip-in-isolate_migratepages_range.patch
> 
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>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Subject: mm/compaction.c: avoid premature range skip in isolate_migratepages_range
> 
> commit edc2ca612496 ("mm, compaction: move pageblock checks up from
> isolate_migratepages_range()") commonizes isolate_migratepages variants
> and make them use isolate_migratepages_block().
> 
> isolate_migratepages_block() could stop the execution when enough pages
> are isolated, but, there is no code in isolate_migratepages_range() to
> handle this case.  In the result, even if isolate_migratepages_block()
> returns prematurely without checking all pages in the range,
> 
> isolate_migratepages_block() is called repeately on the following
> pageblock and some pages in the previous range are skipped to check.
> Then, CMA is failed frequently due to this fact.
> 
> To fix this problem, this patch let isolate_migratepages_range() know the
> situation that enough pages are isolated and stop the isolation in that
> case.
> 
> Note that isolate_migratepages() has no such problem, because, it always
> stops the isolation after just one call of isolate_migratepages_block().
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

Hello, Andrew.

I forgot to mention that this should be merged for v3.18. :)

Thanks.
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