---

yaml
---
r: 28924
b: refs/heads/master
c: 5b5c712
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e7340f73307abed9283d0a07570d06e228c205dd
+refs/heads/master: 5b5c7120e2154239837fad5e3c7b7b781092b19c

trunk/mm/migrate.c

@@ -168,19 +168,19 @@ static int swap_page(struct page *page)
 /*
  * Remove references for a page and establish the new page with the correct
  * basic settings to be able to stop accesses to the page.
+ *
+ * The number of remaining references must be:
+ * 1 for anonymous pages without a mapping
+ * 2 for pages with a mapping
+ * 3 for pages with a mapping and PagePrivate set.
  */
 static int migrate_page_remove_references(struct page *newpage,
-				struct page *page, int nr_refs)
+				struct page *page)
 {
 	struct address_space *mapping = page_mapping(page);
 	struct page **radix_pointer;
 
-	/*
-	 * Avoid doing any of the following work if the page count
-	 * indicates that the page is in use or truncate has removed
-	 * the page.
-	 */
-	if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
+	if (!mapping)
 		return -EAGAIN;
 
 	/*
@@ -218,7 +218,8 @@ static int migrate_page_remove_references(struct page *newpage,
 						&mapping->page_tree,
 						page_index(page));
 
-	if (!page_mapping(page) || page_count(page) != nr_refs ||
+	if (!page_mapping(page) ||
+			page_count(page) != 2 + !!PagePrivate(page) ||
 			*radix_pointer != page) {
 		write_unlock_irq(&mapping->tree_lock);
 		return -EAGAIN;
@@ -309,7 +310,7 @@ int migrate_page(struct page *newpage, struct page *page)
 
 	BUG_ON(PageWriteback(page));	/* Writeback must be complete */
 
-	rc = migrate_page_remove_references(newpage, page, 2);
+	rc = migrate_page_remove_references(newpage, page);
 
 	if (rc)
 		return rc;
@@ -348,7 +349,7 @@ int buffer_migrate_page(struct page *newpage, struct page *page)
 
 	head = page_buffers(page);
 
-	rc = migrate_page_remove_references(newpage, page, 3);
+	rc = migrate_page_remove_references(newpage, page);
 
 	if (rc)
 		return rc;