X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fmigrate.c;h=e2fdbce1874b4ff7a481621b6c5a3285d8d75260;hb=ba0268a8b056f2ad846f1f8837a764c21bb6425e;hp=37c73b902008e1dd2083f71995f2ce67975f6512;hpb=7b5573769f26a23518b33a64ec129d2833564877;p=linux-2.6

diff --git a/mm/migrate.c b/mm/migrate.c
index 37c73b9020..e2fdbce187 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -611,6 +611,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 	int rc = 0;
 	int *result = NULL;
 	struct page *newpage = get_new_page(page, private, &result);
+	int rcu_locked = 0;
 
 	if (!newpage)
 		return -ENOMEM;
@@ -636,8 +637,13 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 	 * we cannot notice that anon_vma is freed while we migrates a page.
 	 * This rcu_read_lock() delays freeing anon_vma pointer until the end
 	 * of migration. File cache pages are no problem because of page_lock()
+	 * File Caches may use write_page() or lock_page() in migration, then,
+	 * just care Anon page here.
 	 */
-	rcu_read_lock();
+	if (PageAnon(page)) {
+		rcu_read_lock();
+		rcu_locked = 1;
+	}
 	/*
 	 * This is a corner case handling.
 	 * When a new swap-cache is read into, it is linked to LRU
@@ -656,7 +662,8 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 	if (rc)
 		remove_migration_ptes(page, page);
 rcu_unlock:
-	rcu_read_unlock();
+	if (rcu_locked)
+		rcu_read_unlock();
 
 unlock: