[RFC PATCH 08/14] mm: use __page_cache_release() in folios_put()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Pass a pointer to the lruvec so we can take advantage of the
folio_lruvec_relock_irqsave().  Adjust the calling convention of
folio_lruvec_relock_irqsave() to suit and add a page_cache_release()
wrapper.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/memcontrol.h | 16 +++++-----
 mm/swap.c                  | 62 ++++++++++++++++++--------------------
 2 files changed, 37 insertions(+), 41 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d0caeb1c1136..44d3e459d16f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1666,18 +1666,18 @@ static inline struct lruvec *folio_lruvec_relock_irq(struct folio *folio,
 	return folio_lruvec_lock_irq(folio);
 }
 
-/* Don't lock again iff page's lruvec locked */
-static inline struct lruvec *folio_lruvec_relock_irqsave(struct folio *folio,
-		struct lruvec *locked_lruvec, unsigned long *flags)
+/* Don't lock again iff folio's lruvec locked */
+static inline void folio_lruvec_relock_irqsave(struct folio *folio,
+		struct lruvec **lruvecp, unsigned long *flags)
 {
-	if (locked_lruvec) {
-		if (folio_matches_lruvec(folio, locked_lruvec))
-			return locked_lruvec;
+	if (*lruvecp) {
+		if (folio_matches_lruvec(folio, *lruvecp))
+			return;
 
-		unlock_page_lruvec_irqrestore(locked_lruvec, *flags);
+		unlock_page_lruvec_irqrestore(*lruvecp, *flags);
 	}
 
-	return folio_lruvec_lock_irqsave(folio, flags);
+	*lruvecp = folio_lruvec_lock_irqsave(folio, flags);
 }
 
 #ifdef CONFIG_CGROUP_WRITEBACK
diff --git a/mm/swap.c b/mm/swap.c
index fffdb48cfbf9..21c2df0f7928 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -74,22 +74,21 @@ static DEFINE_PER_CPU(struct cpu_fbatches, cpu_fbatches) = {
 	.lock = INIT_LOCAL_LOCK(lock),
 };
 
-/*
- * This path almost never happens for VM activity - pages are normally freed
- * in batches.  But it gets used by networking - and for compound pages.
- */
-static void __page_cache_release(struct folio *folio)
+static void __page_cache_release(struct folio *folio, struct lruvec **lruvecp,
+		unsigned long *flagsp)
 {
 	if (folio_test_lru(folio)) {
-		struct lruvec *lruvec;
-		unsigned long flags;
-
-		lruvec = folio_lruvec_lock_irqsave(folio, &flags);
-		lruvec_del_folio(lruvec, folio);
+		folio_lruvec_relock_irqsave(folio, lruvecp, flagsp);
+		lruvec_del_folio(*lruvecp, folio);
 		__folio_clear_lru_flags(folio);
-		unlock_page_lruvec_irqrestore(lruvec, flags);
 	}
-	/* See comment on folio_test_mlocked in folios_put() */
+
+	/*
+	 * In rare cases, when truncation or holepunching raced with
+	 * munlock after VM_LOCKED was cleared, Mlocked may still be
+	 * found set here.  This does not indicate a problem, unless
+	 * "unevictable_pgs_cleared" appears worryingly large.
+	 */
 	if (unlikely(folio_test_mlocked(folio))) {
 		long nr_pages = folio_nr_pages(folio);
 
@@ -99,9 +98,23 @@ static void __page_cache_release(struct folio *folio)
 	}
 }
 
+/*
+ * This path almost never happens for VM activity - pages are normally freed
+ * in batches.  But it gets used by networking - and for compound pages.
+ */
+static void page_cache_release(struct folio *folio)
+{
+	struct lruvec *lruvec = NULL;
+	unsigned long flags;
+
+	__page_cache_release(folio, &lruvec, &flags);
+	if (lruvec)
+		unlock_page_lruvec_irqrestore(lruvec, flags);
+}
+
 static void __folio_put_small(struct folio *folio)
 {
-	__page_cache_release(folio);
+	page_cache_release(folio);
 	mem_cgroup_uncharge(folio);
 	free_unref_page(&folio->page, 0);
 }
@@ -115,7 +128,7 @@ static void __folio_put_large(struct folio *folio)
 	 * be called for hugetlb (it has a separate hugetlb_cgroup.)
 	 */
 	if (!folio_test_hugetlb(folio))
-		__page_cache_release(folio);
+		page_cache_release(folio);
 	destroy_large_folio(folio);
 }
 
@@ -216,7 +229,7 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
 		if (move_fn != lru_add_fn && !folio_test_clear_lru(folio))
 			continue;
 
-		lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
+		folio_lruvec_relock_irqsave(folio, &lruvec, &flags);
 		move_fn(lruvec, folio);
 
 		folio_set_lru(folio);
@@ -996,24 +1009,7 @@ void folios_put(struct folio_batch *folios)
 			continue;
 		}
 
-		if (folio_test_lru(folio)) {
-			lruvec = folio_lruvec_relock_irqsave(folio, lruvec,
-									&flags);
-			lruvec_del_folio(lruvec, folio);
-			__folio_clear_lru_flags(folio);
-		}
-
-		/*
-		 * In rare cases, when truncation or holepunching raced with
-		 * munlock after VM_LOCKED was cleared, Mlocked may still be
-		 * found set here.  This does not indicate a problem, unless
-		 * "unevictable_pgs_cleared" appears worryingly large.
-		 */
-		if (unlikely(folio_test_mlocked(folio))) {
-			__folio_clear_mlocked(folio);
-			zone_stat_sub_folio(folio, NR_MLOCK);
-			count_vm_event(UNEVICTABLE_PGCLEARED);
-		}
+		__page_cache_release(folio, &lruvec, &flags);
 
 		if (j != i)
 			folios->folios[j] = folio;
-- 
2.40.1