[PATCH RFC 07/15] mm/mglru: move refault workingset activation into lru_gen_refault

Move the folio_set_active() for refaulted workingset folios from
folio_add_lru() into lru_gen_refault(), where the refault detection
already happens.  No functional change: the ordering and logic are
preserved in all cases, and no other paths reach the removed branch.

This is a preparatory cleanup for MGLRU-FG.
---
 mm/folio.c      | 6 +-----
 mm/workingset.c | 9 ++++-----
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/mm/folio.c b/mm/folio.c
index f90b7f86dbe3..fab00cb02970 100644
--- a/mm/folio.c
+++ b/mm/folio.c
@@ -474,17 +474,13 @@ void folio_add_lru(struct folio *folio)
 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
 
 	/*
-	 * For refaulted workingset folios, set PG_active so they
-	 * can be added to active generations.
 	 * For prefaulted file folios, folio_mark_accessed() sets
 	 * PG_referenced so lru_gen_folio_seq() places them into
 	 * the second oldest generation.
 	 */
 	if (lru_gen_enabled() && !folio_test_unevictable(folio) &&
 	    lru_gen_in_fault() && !(current->flags & PF_MEMALLOC)) {
-		if (folio_test_workingset(folio))
-			folio_set_active(folio);
-		else if (!folio_test_referenced(folio))
+		if (!folio_test_referenced(folio) && !folio_test_workingset(folio))
 			folio_mark_accessed(folio);
 	}
 
diff --git a/mm/workingset.c b/mm/workingset.c
index 7ac2b88c80ae..5438e9390011 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -320,12 +320,11 @@ static void lru_gen_refault(struct folio *folio, void *shadow)
 	atomic_long_add(delta, &lrugen->refaulted[hist][type][tier]);
 
 	if (workingset) {
-		/*
-		 * see folio_add_lru(), where folio_set_active() is
-		 * called for workingset folios
-		 */
-		if (lru_gen_in_fault())
+		/* Send refaulted workingset folios to active generations. */
+		if (lru_gen_in_fault()) {
+			folio_set_active(folio);
 			mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta);
+		}
 		folio_set_workingset(folio);
 		mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta);
 	} else

-- 
2.55.0