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

Yuanchu Xie
2026-03-17T19:55:28Z

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>