1 files changed, 114 insertions, 83 deletions

diff --git a/mm/swap.c b/mm/swap.c
index cd8f0150ba..500a09a48d 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 release_pages() */
+
+	/*
+	 * 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);
 }
 
@@ -138,22 +151,25 @@ EXPORT_SYMBOL(__folio_put);
  */
 void put_pages_list(struct list_head *pages)
 {
+	struct folio_batch fbatch;
 	struct folio *folio, *next;
 
+	folio_batch_init(&fbatch);
 	list_for_each_entry_safe(folio, next, pages, lru) {
-		if (!folio_put_testzero(folio)) {
-			list_del(&folio->lru);
+		if (!folio_put_testzero(folio))
 			continue;
-		}
 		if (folio_test_large(folio)) {
-			list_del(&folio->lru);
 			__folio_put_large(folio);
 			continue;
 		}
 		/* LRU flag must be clear because it's passed using the lru */
+		if (folio_batch_add(&fbatch, folio) > 0)
+			continue;
+		free_unref_folios(&fbatch);
 	}
 
-	free_unref_page_list(pages);
+	if (fbatch.nr)
+		free_unref_folios(&fbatch);
 	INIT_LIST_HEAD(pages);
 }
 EXPORT_SYMBOL(put_pages_list);
@@ -175,7 +191,7 @@ static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)
 	 * while the LRU lock is held.
 	 *
 	 * (That is not true of __page_cache_release(), and not necessarily
-	 * true of release_pages(): but those only clear the mlocked flag after
+	 * true of folios_put(): but those only clear the mlocked flag after
 	 * folio_put_testzero() has excluded any other users of the folio.)
 	 */
 	if (folio_evictable(folio)) {
@@ -213,7 +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);
@@ -221,8 +237,7 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
 
 	if (lruvec)
 		unlock_page_lruvec_irqrestore(lruvec, flags);
-	folios_put(fbatch->folios, folio_batch_count(fbatch));
-	folio_batch_reinit(fbatch);
+	folios_put(fbatch);
 }
 
 static void folio_batch_add_and_move(struct folio_batch *fbatch,
@@ -946,41 +961,29 @@ void lru_cache_disable(void)
 }
 
 /**
- * release_pages - batched put_page()
- * @arg: array of pages to release
- * @nr: number of pages
+ * folios_put_refs - Reduce the reference count on a batch of folios.
+ * @folios: The folios.
+ * @refs: The number of refs to subtract from each folio.
  *
- * Decrement the reference count on all the pages in @arg.  If it
- * fell to zero, remove the page from the LRU and free it.
+ * Like folio_put(), but for a batch of folios.  This is more efficient
+ * than writing the loop yourself as it will optimise the locks which need
+ * to be taken if the folios are freed.  The folios batch is returned
+ * empty and ready to be reused for another batch; there is no need
+ * to reinitialise it.  If @refs is NULL, we subtract one from each
+ * folio refcount.
  *
- * Note that the argument can be an array of pages, encoded pages,
- * or folio pointers. We ignore any encoded bits, and turn any of
- * them into just a folio that gets free'd.
+ * Context: May be called in process or interrupt context, but not in NMI
+ * context.  May be called while holding a spinlock.
  */
-void release_pages(release_pages_arg arg, int nr)
+void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
 {
-	int i;
-	struct encoded_page **encoded = arg.encoded_pages;
-	LIST_HEAD(pages_to_free);
+	int i, j;
 	struct lruvec *lruvec = NULL;
 	unsigned long flags = 0;
-	unsigned int lock_batch;
 
-	for (i = 0; i < nr; i++) {
-		struct folio *folio;
-
-		/* Turn any of the argument types into a folio */
-		folio = page_folio(encoded_page_ptr(encoded[i]));
-
-		/*
-		 * Make sure the IRQ-safe lock-holding time does not get
-		 * excessive with a continuous string of pages from the
-		 * same lruvec. The lock is held only if lruvec != NULL.
-		 */
-		if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
-			unlock_page_lruvec_irqrestore(lruvec, flags);
-			lruvec = NULL;
-		}
+	for (i = 0, j = 0; i < folios->nr; i++) {
+		struct folio *folio = folios->folios[i];
+		unsigned int nr_refs = refs ? refs[i] : 1;
 
 		if (is_huge_zero_page(&folio->page))
 			continue;
@@ -990,56 +993,85 @@ void release_pages(release_pages_arg arg, int nr)
 				unlock_page_lruvec_irqrestore(lruvec, flags);
 				lruvec = NULL;
 			}
-			if (put_devmap_managed_page(&folio->page))
+			if (put_devmap_managed_page_refs(&folio->page, nr_refs))
 				continue;
-			if (folio_put_testzero(folio))
+			if (folio_ref_sub_and_test(folio, nr_refs))
 				free_zone_device_page(&folio->page);
 			continue;
 		}
 
-		if (!folio_put_testzero(folio))
+		if (!folio_ref_sub_and_test(folio, nr_refs))
 			continue;
 
-		if (folio_test_large(folio)) {
+		/* hugetlb has its own memcg */
+		if (folio_test_hugetlb(folio)) {
 			if (lruvec) {
 				unlock_page_lruvec_irqrestore(lruvec, flags);
 				lruvec = NULL;
 			}
-			__folio_put_large(folio);
+			free_huge_folio(folio);
 			continue;
 		}
+		if (folio_test_large(folio) &&
+		    folio_test_large_rmappable(folio))
+			folio_undo_large_rmappable(folio);
 
-		if (folio_test_lru(folio)) {
-			struct lruvec *prev_lruvec = lruvec;
+		__page_cache_release(folio, &lruvec, &flags);
 
-			lruvec = folio_lruvec_relock_irqsave(folio, lruvec,
-									&flags);
-			if (prev_lruvec != lruvec)
-				lock_batch = 0;
+		if (j != i)
+			folios->folios[j] = folio;
+		j++;
+	}
+	if (lruvec)
+		unlock_page_lruvec_irqrestore(lruvec, flags);
+	if (!j) {
+		folio_batch_reinit(folios);
+		return;
+	}
 
-			lruvec_del_folio(lruvec, folio);
-			__folio_clear_lru_flags(folio);
-		}
+	folios->nr = j;
+	mem_cgroup_uncharge_folios(folios);
+	free_unref_folios(folios);
+}
+EXPORT_SYMBOL(folios_put_refs);
 
-		/*
-		 * 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);
-		}
+/**
+ * release_pages - batched put_page()
+ * @arg: array of pages to release
+ * @nr: number of pages
+ *
+ * Decrement the reference count on all the pages in @arg.  If it
+ * fell to zero, remove the page from the LRU and free it.
+ *
+ * Note that the argument can be an array of pages, encoded pages,
+ * or folio pointers. We ignore any encoded bits, and turn any of
+ * them into just a folio that gets free'd.
+ */
+void release_pages(release_pages_arg arg, int nr)
+{
+	struct folio_batch fbatch;
+	int refs[PAGEVEC_SIZE];
+	struct encoded_page **encoded = arg.encoded_pages;
+	int i;
+
+	folio_batch_init(&fbatch);
+	for (i = 0; i < nr; i++) {
+		/* Turn any of the argument types into a folio */
+		struct folio *folio = page_folio(encoded_page_ptr(encoded[i]));
+
+		/* Is our next entry actually "nr_pages" -> "nr_refs" ? */
+		refs[fbatch.nr] = 1;
+		if (unlikely(encoded_page_flags(encoded[i]) &
+			     ENCODED_PAGE_BIT_NR_PAGES_NEXT))
+			refs[fbatch.nr] = encoded_nr_pages(encoded[++i]);
 
-		list_add(&folio->lru, &pages_to_free);
+		if (folio_batch_add(&fbatch, folio) > 0)
+			continue;
+		folios_put_refs(&fbatch, refs);
 	}
-	if (lruvec)
-		unlock_page_lruvec_irqrestore(lruvec, flags);
 
-	mem_cgroup_uncharge_list(&pages_to_free);
-	free_unref_page_list(&pages_to_free);
+	if (fbatch.nr)
+		folios_put_refs(&fbatch, refs);
 }
 EXPORT_SYMBOL(release_pages);
 
@@ -1059,8 +1091,7 @@ void __folio_batch_release(struct folio_batch *fbatch)
 		lru_add_drain();
 		fbatch->percpu_pvec_drained = true;
 	}
-	release_pages(fbatch->folios, folio_batch_count(fbatch));
-	folio_batch_reinit(fbatch);
+	folios_put(fbatch);
 }
 EXPORT_SYMBOL(__folio_batch_release);