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

Kairui Song via B4 Relay
2026-03-17T19:11:51Z

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