From 02a5f215a2f78199690b28d139ef534818e231b7 Mon Sep 17 00:00:00 2001
From: Christoph Lameter <clameter@sgi.com>
Date: Fri, 23 Jun 2006 02:03:29 -0700
Subject: [PATCH] --- yaml --- r: 28924 b: refs/heads/master c:
 5b5c7120e2154239837fad5e3c7b7b781092b19c h: refs/heads/master v: v3

---
 [refs]             |  2 +-
 trunk/mm/migrate.c | 21 +++++++++++----------
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/[refs] b/[refs]
index 1fe478976c24..98d19b4a950a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e7340f73307abed9283d0a07570d06e228c205dd
+refs/heads/master: 5b5c7120e2154239837fad5e3c7b7b781092b19c
diff --git a/trunk/mm/migrate.c b/trunk/mm/migrate.c
index be3f141e53a4..2803a6698dd6 100644
--- a/trunk/mm/migrate.c
+++ b/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;