Re: [PATCH v5 2/4] mm: workingset: use lruvec_page_state_local() to count lru pages

[Barry Song]

On Fri, Sep 11, 2026 at 4:01 PM Hui Zhu <hui.zhu@xxxxxxxxx> wrote:
>
> From: Hui Zhu <zhuhui@xxxxxxxxxx>
>
> Commit 7404bd37cfbe ("mm: workingset: use lruvec_lru_size() to get the
> number of lru pages") switched count_shadow_nodes() to lruvec_lru_size().
> With CONFIG_MEMCG enabled, lruvec_lru_size() reads mz->lru_zone_size,
> which only the classic LRU paths maintain.  MGLRU accounts its pages
> through __update_lru_size(), which skips that array, so with MGLRU on the
> four evictable LRU lists are always seen as empty.  The shadow node budget
> (pages >> 3) then collapses to slab plus unevictable pages, and the
> workingset shadow shrinker reclaims eviction tokens almost as fast as they
> are created, losing thrashing protection.
>
> lruvec_page_state_local() reads lruvec_stats->state_local instead, which
> both classic LRU and MGLRU maintain.  Switch back to it.  The reparenting
> race this re-exposes on cgroup v2 is closed by the preceding patch that
> redirects dying-memcg stat updates for all hierarchies.
>
> Fixes: 7404bd37cfbe ("mm: workingset: use lruvec_lru_size() to get the number of lru pages")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>
> Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> ---

Reviewed-by: Barry Song <baohua@xxxxxxxxxx>