[PATCH v6 11/15] mm/mglru: Restrict eviction accounting to eligible zones

["Barry Song (Xiaomi)" <baohua@kernel.org>]

For both lruvec_evictable_size() and lru_gen_imbalanced(),
only count eligible zones below sc->reclaim_idx. This
avoids inflating the number of scanned pages and allows
aging to proceed more promptly when eligible zones have
few folios.

Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
---
 mm/trace_vmscan.h | 4 ++--
 mm/vmscan.c       | 8 ++++----
 mm/vmscan.h       | 5 +++--
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/mm/trace_vmscan.h b/mm/trace_vmscan.h
index 565c56428364..9dafdb5bd3ce 100644
--- a/mm/trace_vmscan.h
+++ b/mm/trace_vmscan.h
@@ -488,9 +488,9 @@ TRACE_EVENT(mm_mglru_aging,
 			unsigned long seq = max_seq - MAX_NR_GENS + 1 + i;
 
 			__entry->nr_anon[i] =
-				lruvec_gen_size(lrugen, LRU_GEN_ANON, seq);
+				lruvec_gen_size(lrugen, LRU_GEN_ANON, seq, MAX_NR_ZONES);
 			__entry->nr_file[i] =
-				lruvec_gen_size(lrugen, LRU_GEN_FILE, seq);
+				lruvec_gen_size(lrugen, LRU_GEN_FILE, seq, MAX_NR_ZONES);
 		}
 		__entry->nid = lruvec_pgdat(lruvec)->node_id;
 		__entry->priority = sc->priority;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8014a90e4bc2..bfc9789a999a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4220,7 +4220,7 @@ static void lruvec_evictable_size(struct lruvec *lruvec, int swappiness,
 
 	for_each_evictable_type(type, swappiness) {
 		for (seq = min_seq[type]; seq <= max_seq; seq++)
-			nr[type] += lruvec_gen_size(lrugen, type, seq);
+			nr[type] += lruvec_gen_size(lrugen, type, seq, sc->reclaim_idx + 1);
 	}
 }
 
@@ -5080,9 +5080,9 @@ static bool lru_gen_imbalanced(struct lruvec *lruvec, struct scan_control *sc,
 	for_each_evictable_type(type, swappiness) {
 		unsigned long seq;
 
-		youngest[type] = lruvec_gen_size(lrugen, type, max_seq);
+		youngest[type] = lruvec_gen_size(lrugen, type, max_seq, sc->reclaim_idx + 1);
 		for (seq = min_seq[type]; seq < max_seq; seq++)
-			old[type] += lruvec_gen_size(lrugen, type, seq);
+			old[type] += lruvec_gen_size(lrugen, type, seq, sc->reclaim_idx + 1);
 	}
 
 	/* the vast majority of pages sit in the youngest gen */
@@ -5826,7 +5826,7 @@ static int lru_gen_seq_show(struct seq_file *m, void *v)
 			char mark = full && seq < min_seq[type] ? 'x' : ' ';
 
 			seq_printf(m, " %10lu%c",
-				   lruvec_gen_size(lrugen, type, seq), mark);
+				   lruvec_gen_size(lrugen, type, seq, MAX_NR_ZONES), mark);
 		}
 
 		seq_putc(m, '\n');
diff --git a/mm/vmscan.h b/mm/vmscan.h
index c6b583fc7493..2599d7c614ac 100644
--- a/mm/vmscan.h
+++ b/mm/vmscan.h
@@ -119,12 +119,13 @@ struct scan_control {
 #ifdef CONFIG_LRU_GEN
 /* The number of pages of @type in the generation @seq, summed over all zones */
 static inline unsigned long lruvec_gen_size(struct lru_gen_folio *lrugen,
-					    int type, unsigned long seq)
+					    int type, unsigned long seq,
+					    int max_zone)
 {
 	int gen = lru_gen_from_seq(seq);
 	unsigned long size = 0;
 
-	for (int zone = 0; zone < MAX_NR_ZONES; zone++)
+	for (int zone = 0; zone < max_zone; zone++)
 		size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
 
 	return size;
-- 
2.34.1