linux-kernel - [PATCH V4 4/4] mm: using SWAPPINESS_ANON

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Message-Id: <529db7ae6098ee712b81e4df290622e4e64ac50c.1745225696.git.hezhongkun.hzk@bytedance.com>
Date: Mon, 21 Apr 2025 17:13:31 +0800
From: Zhongkun He <hezhongkun.hzk@...edance.com>
To: akpm@...ux-foundation.org
Cc: hannes@...xchg.org,
	mhocko@...e.com,
	yosry.ahmed@...ux.dev,
	muchun.song@...ux.dev,
	yuzhao@...gle.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Zhongkun He <hezhongkun.hzk@...edance.com>
Subject: [PATCH V4 4/4] mm: using SWAPPINESS_ANON_ONLY in MGLRU

Using SWAPPINESS_ANON_ONLY instead of MAX_SWAPPINESS + 1
to indicate reclaiming only from anonymous pages makes the
code more readable and explicit.

Add some comment in the SWAPPINESS_ANON_ONLY context.

Signed-off-by: Zhongkun He <hezhongkun.hzk@...edance.com>
---
 mm/vmscan.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index b442c20d1168..24e959881ada 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2698,8 +2698,12 @@ static bool should_clear_pmd_young(void)
 		READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_FILE]),	\
 	}
 
+/* Get the min/max evictable type based on swappiness */
+#define min_type(swappiness) (!(swappiness))
+#define max_type(swappiness) ((swappiness) < SWAPPINESS_ANON_ONLY)
+
 #define evictable_min_seq(min_seq, swappiness)				\
-	min((min_seq)[!(swappiness)], (min_seq)[(swappiness) <= MAX_SWAPPINESS])
+	min((min_seq)[min_type(swappiness)], (min_seq)[max_type(swappiness)])
 
 #define for_each_gen_type_zone(gen, type, zone)				\
 	for ((gen) = 0; (gen) < MAX_NR_GENS; (gen)++)			\
@@ -2707,7 +2711,7 @@ static bool should_clear_pmd_young(void)
 			for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++)
 
 #define for_each_evictable_type(type, swappiness)			\
-	for ((type) = !(swappiness); (type) <= ((swappiness) <= MAX_SWAPPINESS); (type)++)
+	for ((type) = min_type(swappiness); (type) <= max_type(swappiness); (type)++)
 
 #define get_memcg_gen(seq)	((seq) % MEMCG_NR_GENS)
 #define get_memcg_bin(bin)	((bin) % MEMCG_NR_BINS)
@@ -3858,7 +3862,12 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness)
 	int hist = lru_hist_from_seq(lrugen->min_seq[type]);
 	int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
 
-	if (type ? swappiness > MAX_SWAPPINESS : !swappiness)
+	/* For file type, skip the check if swappiness is anon only */
+	if (type && (swappiness == SWAPPINESS_ANON_ONLY))
+		goto done;
+
+	/* For anon type, skip the check if swappiness is zero (file only) */
+	if (!type && !swappiness)
 		goto done;
 
 	/* prevent cold/hot inversion if the type is evictable */
@@ -5524,7 +5533,7 @@ static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
 
 	if (swappiness < MIN_SWAPPINESS)
 		swappiness = get_swappiness(lruvec, sc);
-	else if (swappiness > MAX_SWAPPINESS + 1)
+	else if (swappiness > SWAPPINESS_ANON_ONLY)
 		goto done;
 
 	switch (cmd) {
-- 
2.39.5