mm/ksm: use ksm_get_folio in scan_get_next_rmap_item

Save a compound_head call.

Link: https://lkml.kernel.org/r/20240411061713.1847574-7-alexs@kernel.orgSigned-off-by: Alex Shi (tencent) <alexs@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/ksm.c

@@ -2611,14 +2611,14 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
 		 */
 		if (!ksm_merge_across_nodes) {
 			struct ksm_stable_node *stable_node, *next;
-			struct page *page;
+			struct folio *folio;
 
 			list_for_each_entry_safe(stable_node, next,
 						 &migrate_nodes, list) {
-				page = get_ksm_page(stable_node,
+				folio = ksm_get_folio(stable_node,
 						      GET_KSM_PAGE_NOLOCK);
-				if (page)
-					put_page(page);
+				if (folio)
+					folio_put(folio);
 				cond_resched();
 			}
 		}