Re: [PATCH v3 19/32] hugepage: convert huge zero page shrinker to new shrinker API

Greg Thelen
2013-04-15T05:38:37Z

On Mon, Apr 08 2013, Glauber Costa wrote:

> It consists of:
>
> * returning long instead of int
> * separating count from scan
> * returning the number of freed entities in scan
>
> Signed-off-by: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
> CC: Dave Chinner <dchinner-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Reviewed-by: Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

> ---
> mm/huge_memory.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index e2f7f5aa..8bf43d3 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -212,24 +212,30 @@ static void put_huge_zero_page(void)
> BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
> }
>
> -static int shrink_huge_zero_page(struct shrinker *shrink,
> - struct shrink_control *sc)
> +
> +static long shrink_huge_zero_page_count(struct shrinker *shrink,
> + struct shrink_control *sc)
> {
> - if (!sc->nr_to_scan)
> - /* we can free zero page only if last reference remains */
> - return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
> + /* we can free zero page only if last reference remains */
> + return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
> +}
>
> +static long shrink_huge_zero_page_scan(struct shrinker *shrink,
> + struct shrink_control *sc)
> +{
> if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
> unsigned long zero_pfn = xchg(&huge_zero_pfn, 0);
> BUG_ON(zero_pfn == 0);
> __free_page(__pfn_to_page(zero_pfn));
> + return HPAGE_PMD_NR;
> }
>
> return 0;
> }
>
> static struct shrinker huge_zero_page_shrinker = {
> - .shrink = shrink_huge_zero_page,
> + .scan_objects = shrink_huge_zero_page_scan,
> + .count_objects = shrink_huge_zero_page_count,
> .seeks = DEFAULT_SEEKS,
> };