Re: [RFC PATCH v5 06/14] mm/mglru: return for unavailable anon reclaim earlier

[KunWu Chan]

On Fri, Oct 23, 2026 at 6:02 AM Barry Song (Xiaomi) <baohua@xxxxxxxxxx> wrote:
>
> From: Kairui Song <kasong@xxxxxxxxxxx>
>
> No feature change, just shuffle some code, prepare for later commits.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> Signed-off-by: Barry Song (Xiaomi) <baohua@xxxxxxxxxx>
> ---
>  mm/vmscan.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index d3caed8aa789..0930bee5906e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -5215,20 +5215,6 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
>                            struct mem_cgroup *memcg, int swappiness)
>  {
>         unsigned long nr_to_scan, evictable, sizes[ANON_AND_FILE];
> -       struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> -
> -       /*
> -        * Proactive reclaim initiated by userspace for anonymous memory only.
> -        * SWAPPINESS_ANON_ONLY is set only on the proactive reclaim path, so
> -        * warn if it shows up elsewhere. When anon cannot be reclaimed (e.g.
> -        * no swap), return 0 to skip the scan entirely, avoiding useless scan
> -        * work when there is nothing eligible to reclaim.
> -        */
> -       if (swappiness == SWAPPINESS_ANON_ONLY) {
> -               WARN_ON_ONCE(!sc->proactive);
> -               if (!can_reclaim_anon_pages(memcg, pgdat->node_id, sc))
> -                       return 0;
> -       }
>
>         lruvec_evictable_size(lruvec, swappiness, sizes);
>         evictable = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
> @@ -5285,6 +5271,19 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
>         int swappiness = get_swappiness(lruvec, sc);
>         struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>
> +       /*
> +        * Proactive reclaim initiated by userspace for anonymous memory only.
> +        * SWAPPINESS_ANON_ONLY is set only on the proactive reclaim path, so
> +        * warn if it shows up elsewhere. When anon cannot be reclaimed (e.g.
> +        * no swap), return 0 to skip the scan entirely, avoiding useless scan
> +        * work when there is nothing eligible to reclaim.
> +        */
> +       if (swappiness == SWAPPINESS_ANON_ONLY) {
> +               WARN_ON_ONCE(!sc->proactive);
> +               if (!can_reclaim_anon_pages(memcg, lruvec_pgdat(lruvec)->node_id, sc))
> +                       return false;
> +       }
> +
>         nr_to_scan = get_nr_to_scan(lruvec, sc, memcg, swappiness);
>         while (nr_to_scan > 0) {
>                 int delta;
> --
> 2.34.1
>

Pure code movement. Identical check, same result, earlier return.

Reviewed-by: Kunwu Chan <kunwu.chan@xxxxxxxxx>