[v2,04/10] mm: compaction: try get reference before non-lru movable folio migration

Commit Message

Kefeng Wang April 25, 2024, 8:40 a.m. UTC

Non-lru movable folio migration will fail if !folio_get_nontail_page(),
see isolate_movable_page(), so does lru folio, so folio_get_nontail_page()
could be called firstly to unify the handling of non-lru movable/lru folios
migration a bit, this is also to prepare to convert isolate_movable_page()
to take a folio. Since the reference count of the non-lru movable folio is
increased, a folio_put() is needed whether the folio is isolated or not.

Signed-off-by: Kefeng Wang <[e-mail]>
---
 mm/compaction.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

Patch

diff --git a/mm/compaction.c b/mm/compaction.c
index e731d45befc7..4fc5a19b06ad 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1097,41 +1097,41 @@  isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			}
 		}
 
+		/*
+		 * Be careful not to clear LRU flag until after we're
+		 * sure the folio is not being freed elsewhere -- the
+		 * folio release code relies on it.
+		 */
+		folio = folio_get_nontail_page(page);
+		if (unlikely(!folio))
+			goto isolate_fail;
+
 		/*
 		 * Check may be lockless but that's ok as we recheck later.
-		 * It's possible to migrate LRU and non-lru movable pages.
-		 * Skip any other type of page
+		 * It's possible to migrate LRU and non-lru movable folios.
+		 * Skip any other type of folio
 		 */
-		if (!PageLRU(page)) {
+		if (!folio_test_lru(folio)) {
 			/*
-			 * __PageMovable can return false positive so we need
-			 * to verify it under page_lock.
+			 * __folio_test_movable can return false positive so
+			 * we need to verify it under folio lock.
 			 */
-			if (unlikely(__PageMovable(page)) &&
-					!PageIsolated(page)) {
+			if (unlikely(__folio_test_movable(folio)) &&
+					!folio_test_isolated(folio)) {
 				if (locked) {
 					unlock_page_lruvec_irqrestore(locked, flags);
 					locked = NULL;
 				}
 
-				if (isolate_movable_page(page, mode)) {
-					folio = page_folio(page);
+				if (isolate_movable_page(&folio->page, mode)) {
+					folio_put(folio);
 					goto isolate_success;
 				}
 			}
 
-			goto isolate_fail;
+			goto isolate_fail_put;
 		}
 
-		/*
-		 * Be careful not to clear PageLRU until after we're
-		 * sure the page is not being freed elsewhere -- the
-		 * page release code relies on it.
-		 */
-		folio = folio_get_nontail_page(page);
-		if (unlikely(!folio))
-			goto isolate_fail;
-
 		/*
 		 * Migration will fail if an anonymous page is pinned in memory,
 		 * so avoid taking lru_lock and isolating it unnecessarily in an