Re: [Linaro-mm-sig] [PATCH] mm: skip watermarks check for alreadyisolated blocks in split_free_page()

[Francesco Lavra]

Hi,

On 11/08/2012 07:59 AM, Marek Szyprowski wrote:
> Since commit 2139cbe627b8 ("cma: fix counting of isolated pages") free
> pages in isolated pageblocks are not accounted to NR_FREE_PAGES counters,
> so watermarks check is not required if one operates on a free page in
> isolated pageblock.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
>  mm/page_alloc.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index fd154fe..43ab09f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1394,10 +1394,12 @@ int capture_free_page(struct page *page, int alloc_order, int migratetype)
>  	zone = page_zone(page);
>  	order = page_order(page);
>  
> -	/* Obey watermarks as if the page was being allocated */
> -	watermark = low_wmark_pages(zone) + (1 << order);
> -	if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
> -		return 0;
> +	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) {

get_pageblock_migratetype(page) is also called later on in this function
and assigned to the mt variable: maybe the assignment should be moved
before (or inside) the above line?

--
Francesco
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