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

[Chen Ridong]

On 2026/3/18 3:08, Kairui Song via B4 Relay wrote:
> From: Kairui Song <kasong@xxxxxxxxxxx>
> 
> Merge commonly used code for counting evictable folios in a lruvec.
> 
> No behavior change.
> 
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>

Reviewed-by: Chen Ridong <chenridong@xxxxxxxxxxxxxxx>

> ---
>  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;

I have suffered a lot because of this name. Thank you.

>  	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 */
> 

-- 
Best regards,
Ridong