Re: [PATCH 3/4] mm: move lazy free pages to inactive list

Andrew Morton
2015-03-31T05:26:51Z

On Tue, 31 Mar 2015 13:45:25 +0900 Minchan Kim <minchan@kernel.org> wrote:
> >
> > deactivate_page() doesn't look at or alter PageReferenced(). Should it?
>
> Absolutely true. Thanks.
> Here it goes.
>
> >From 2b2c92eb73a1cceac615b9abd4c0f5f0c3395ff5 Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan@kernel.org>
> Date: Tue, 31 Mar 2015 13:38:46 +0900
> Subject: [PATCH] mm: lru_deactivate_fn should clear PG_referenced
>
> deactivate_page aims for accelerate for reclaiming through
> moving pages from active list to inactive list so we should
> clear PG_referenced for the goal.
>
> ...
>
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -800,6 +800,7 @@ static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
>
> del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
> ClearPageActive(page);
> + ClearPageReferenced(page);
> add_page_to_lru_list(page, lruvec, lru);
>
> __count_vm_event(PGDEACTIVATE);

What if we have

PageLRU(page) && !PageActive(page) && PageReferenced(page)

if we really want to "accelerate the reclaim of @page" then we should
clear PG_referenced there too.

(And what about page_referenced(page) :))