mm: use 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.

Link: https://lkml.kernel.org/r/529db7ae6098ee712b81e4df290622e4e64ac50c.1745225696.git.hezhongkun.hzk@bytedance.com
Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d1ad528186dd81b25b81ca05ac553cba95d5ae3e..7d6d1ce3921e49995ca98db0a2102230726f320f 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2705,8 +2705,12 @@ 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)++)                   \
@@ -2714,7 +2718,7 @@ 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)
@@ -3865,7 +3869,12 @@ 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 */
@@ -5531,7 +5540,7 @@ 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) {