[PATCH RFC 15/15] mm/madvise: convert to new lru refs API and better support for MGLRU

For active/inactive LRU, madvise wants evicted folios from active LRU to
be considered for PSI too, so some special handling are added. But MGLRU
doesn't really need this, as it has a different activation logic.

Switch to new helpers and improve the support for MGLRU here.

Signed-off-by: Kairui Song <[email protected]>
---
 mm/madvise.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index abb17760b8b5..f132dd7418f5 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -350,6 +350,27 @@ static inline int madvise_folio_pte_batch(unsigned long addr, unsigned long end,
 				     FPB_MERGE_YOUNG_DIRTY);
 }
 
+/*
+ * We are deactivating a folio for accelerating reclaiming.
+ * VM couldn't reclaim the folio unless we clear PG_young.
+ * As a side effect, it makes confuse idle-page tracking
+ * because they will miss recent referenced history.
+ */
+static void madvise_cold_or_pageout_prep_folio(struct folio *folio)
+{
+	folio_test_clear_young(folio);
+
+	/*
+	 * MGLRU clears all reference flags in folio_deactivate,
+	 * no need to touch it here.
+	 */
+	if (!lru_gen_enabled()) {
+		folio_clear_referenced_by_bit(folio);
+		if (folio_test_active(folio))
+			folio_mark_workingset_by_bit(folio);
+	}
+}
+
 static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 				unsigned long addr, unsigned long end,
 				struct mm_walk *walk)
@@ -424,10 +445,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 		}
 
-		folio_clear_referenced(folio);
-		folio_test_clear_young(folio);
-		if (folio_test_active(folio))
-			folio_mark_workingset_by_bit(folio);
+		madvise_cold_or_pageout_prep_folio(folio);
 		if (pageout) {
 			if (folio_isolate_lru(folio)) {
 				if (folio_test_unevictable(folio))
@@ -533,16 +551,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			tlb_remove_tlb_entries(tlb, pte, nr, addr);
 		}
 
-		/*
-		 * We are deactivating a folio for accelerating reclaiming.
-		 * VM couldn't reclaim the folio unless we clear PG_young.
-		 * As a side effect, it makes confuse idle-page tracking
-		 * because they will miss recent referenced history.
-		 */
-		folio_clear_referenced(folio);
-		folio_test_clear_young(folio);
-		if (folio_test_active(folio))
-			folio_mark_workingset_by_bit(folio);
+		madvise_cold_or_pageout_prep_folio(folio);
 		if (pageout) {
 			if (folio_isolate_lru(folio)) {
 				if (folio_test_unevictable(folio))

-- 
2.55.0