md: raid6: Fix mktable.c

[linux-2.6-omap-h63xx.git] / mm / migrate.c

diff --git a/mm/migrate.c b/mm/migrate.c
index 4ee4ccacf986e4640d402cc02b1590827379e568..857a987e36904a5850a4d663c6d9e41e494ffe1f 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -640,15 +640,33 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
                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
-        * and treated as swapcache but has no rmap yet.
-        * Calling try_to_unmap() against a page->mapping==NULL page is
-        * BUG. So handle it here.
+        * Corner case handling:
+        * 1. When a new swap-cache page is read into, it is added to the LRU
+        * and treated as swapcache but it has no rmap yet.
+        * Calling try_to_unmap() against a page->mapping==NULL page will
+        * trigger a BUG.  So handle it here.
+        * 2. An orphaned page (see truncate_complete_page) might have
+        * fs-private metadata. The page can be picked up due to memory
+        * offlining.  Everywhere else except page reclaim, the page is
+        * invisible to the vm, so the page can not be migrated.  So try to
+        * free the metadata, so the page can be freed.
         */
-       if (!page->mapping)
+       if (!page->mapping) {
+               if (!PageAnon(page) && PagePrivate(page)) {
+                       /*
+                        * Go direct to try_to_free_buffers() here because
+                        * a) that's what try_to_release_page() would do anyway
+                        * b) we may be under rcu_read_lock() here, so we can't
+                        *    use GFP_KERNEL which is what try_to_release_page()
+                        *    needs to be effective.
+                        */
+                       try_to_free_buffers(page);
+               }
                goto rcu_unlock;
+       }
+
        /* Establish migration ptes or remove ptes */
        try_to_unmap(page, 1);