mm: remove use of folio list from folios_put()

Instead of putting the interesting folios on a list, delete the
uninteresting one from the folio_batch.

Link: https://lkml.kernel.org/r/20240227174254.710559-7-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap.c

@@ -961,12 +961,11 @@ void lru_cache_disable(void)
  */
 void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
 {
-	int i;
-	LIST_HEAD(pages_to_free);
+	int i, j;
 	struct lruvec *lruvec = NULL;
 	unsigned long flags = 0;
 
-	for (i = 0; i < folios->nr; i++) {
+	for (i = 0, j = 0; i < folios->nr; i++) {
 		struct folio *folio = folios->folios[i];
 		unsigned int nr_refs = refs ? refs[i] : 1;
 
@@ -1016,14 +1015,20 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
 			count_vm_event(UNEVICTABLE_PGCLEARED);
 		}
 
-		list_add(&folio->lru, &pages_to_free);
+		if (j != i)
+			folios->folios[j] = folio;
+		j++;
 	}
 	if (lruvec)
 		unlock_page_lruvec_irqrestore(lruvec, flags);
+	if (!j) {
+		folio_batch_reinit(folios);
+		return;
+	}
 
-	mem_cgroup_uncharge_list(&pages_to_free);
-	free_unref_page_list(&pages_to_free);
-	folio_batch_reinit(folios);
+	folios->nr = j;
+	mem_cgroup_uncharge_folios(folios);
+	free_unref_folios(folios);
 }
 EXPORT_SYMBOL(folios_put_refs);