Re: [PATCH 1/8] mm/mglru: consolidate common code for retrieving evitable size

[Yuanchu Xie <yuanchu@google.com>]

Hi Kairui,

On Tue, Mar 17, 2026 at 2:11 PM Kairui Song via B4 Relay
<devnull+kasong.tencent.com@kernel.org> wrote:
>
> From: Kairui Song <kasong@tencent.com>
>
> Merge commonly used code for counting evictable folios in a lruvec.
>
> No behavior change.
>
> Signed-off-by: Kairui Song <kasong@tencent.com>
> ---
>  mm/vmscan.c | 42 +++++++++++++++++-------------------------
>  1 file changed, 17 insertions(+), 25 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 33287ba4a500..d7fc7f1fe06d 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -4078,27 +4078,33 @@ static void set_initial_priority(struct pglist_data *pgdat, struct scan_control
>         sc->priority = clamp(priority, DEF_PRIORITY / 2, DEF_PRIORITY);
>  }
>
> -static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
> +static long lruvec_evictable_size(struct lruvec *lruvec, int swappiness)
>  {
>         int gen, type, zone;
> -       unsigned long total = 0;
> -       int swappiness = get_swappiness(lruvec, sc);
> +       unsigned long seq, total = 0;
>         struct lru_gen_folio *lrugen = &lruvec->lrugen;
> -       struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>         DEFINE_MAX_SEQ(lruvec);
>         DEFINE_MIN_SEQ(lruvec);
>
>         for_each_evictable_type(type, swappiness) {
> -               unsigned long seq;
> -
>                 for (seq = min_seq[type]; seq <= max_seq; seq++) {
>                         gen = lru_gen_from_seq(seq);
> -
>                         for (zone = 0; zone < MAX_NR_ZONES; zone++)
>                                 total += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
>                 }
>         }
>
> +       return total;
> +}
> +
> +static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
> +{
> +       unsigned long total;
> +       int swappiness = get_swappiness(lruvec, sc);
> +       struct mem_cgroup *memcg = lruvec_memcg(lruvec);
> +
> +       total = lruvec_evictable_size(lruvec, swappiness);
> +
>         /* whether the size is big enough to be helpful */
>         return mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
>  }
> @@ -4921,9 +4927,6 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>  static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
>                              int swappiness, unsigned long *nr_to_scan)
>  {
> -       int gen, type, zone;
> -       unsigned long size = 0;
> -       struct lru_gen_folio *lrugen = &lruvec->lrugen;
>         DEFINE_MIN_SEQ(lruvec);
>
>         *nr_to_scan = 0;
> @@ -4931,18 +4934,7 @@ static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
>         if (evictable_min_seq(min_seq, swappiness) + MIN_NR_GENS > max_seq)
>                 return true;
>
> -       for_each_evictable_type(type, swappiness) {
> -               unsigned long seq;
> -
> -               for (seq = min_seq[type]; seq <= max_seq; seq++) {
> -                       gen = lru_gen_from_seq(seq);
> -
> -                       for (zone = 0; zone < MAX_NR_ZONES; zone++)
> -                               size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
> -               }
> -       }
> -
> -       *nr_to_scan = size;
> +       *nr_to_scan = lruvec_evictable_size(lruvec, swappiness);
>         /* better to run aging even though eviction is still possible */
>         return evictable_min_seq(min_seq, swappiness) + MIN_NR_GENS == max_seq;
>  }
> @@ -4954,7 +4946,7 @@ static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
>   */
>  static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, int swappiness)
>  {
> -       bool success;
> +       bool need_aging;
>         unsigned long nr_to_scan;
>         struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>         DEFINE_MAX_SEQ(lruvec);
> @@ -4962,7 +4954,7 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, int s
>         if (mem_cgroup_below_min(sc->target_mem_cgroup, memcg))
>                 return -1;
>
> -       success = should_run_aging(lruvec, max_seq, swappiness, &nr_to_scan);
> +       need_aging = should_run_aging(lruvec, max_seq, swappiness, &nr_to_scan);
>
>         /* try to scrape all its memory if this memcg was deleted */
>         if (nr_to_scan && !mem_cgroup_online(memcg))
> @@ -4971,7 +4963,7 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, int s
>         nr_to_scan = apply_proportional_protection(memcg, sc, nr_to_scan);
>
>         /* try to get away with not aging at the default priority */
> -       if (!success || sc->priority == DEF_PRIORITY)
> +       if (!need_aging || sc->priority == DEF_PRIORITY)
>                 return nr_to_scan >> sc->priority;
>
>         /* stop scanning this lruvec as it's low on cold folios */
>
> --
> 2.53.0
>
>

Yep, the cleanup makes sense.

Acked-by: Yuanchu Xie <yuanchu@google.com>