Re: [PATCH 4/4] mm/compaction: respect ignore_skip_hint in update_pageblock_skip

[Vlastimil Babka]

On 12/06/2013 09:41 AM, Joonsoo Kim wrote:
> update_pageblock_skip() only fits to compaction which tries to isolate by
> pageblock unit. If isolate_migratepages_range() is called by CMA, it try to
> isolate regardless of pageblock unit and it don't reference
> get_pageblock_skip() by ignore_skip_hint. We should also respect it on
> update_pageblock_skip() to prevent from setting the wrong information.

Yeah, this will also prevent updating cached migrate scanner pfn, which 
makes perfect sense, as cma doesn't read them.

> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> diff --git a/mm/compaction.c b/mm/compaction.c
> index 805165b..f58bcd0 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -134,6 +134,10 @@ static void update_pageblock_skip(struct compact_control *cc,
>   			bool migrate_scanner)
>   {
>   	struct zone *zone = cc->zone;
> +
> +	if (cc->ignore_skip_hint)
> +		return;
> +
>   	if (!page)
>   		return;

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