Re: [PATCH v4 5/8] mm/workingset: handle the page without memcg

[Johannes Weiner]

On Mon, Mar 23, 2020 at 02:52:09PM +0900, js1304@xxxxxxxxx wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> 
> When implementing workingset detection for anonymous page, I found
> some swapcache pages with NULL memcg. They are brought in by swap
> readahead and nobody has touched it.
> 
> The idea behind the workingset code is to tell on page fault time
> whether pages have been previously used or not. Since this page
> hasn't been used, don't store a shadow entry for it; when it later
> faults back in, we treat it as the new page that it is.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>