[PATCH] mm: migration page refcounting fix

Migration code currently does not take a reference to target page
properly, so between unlocking the pte and trying to take a new
reference to the page with isolate_lru_page, anything could happen to
it.

Fix this by holding the pte lock until we get a chance to elevate the
refcount.

Other small cleanups while we're here.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 1 insertions, 21 deletions

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 49cc68af01f8..8ac854f7f190 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -39,24 +39,3 @@ del_page_from_lru(struct zone *zone, struct page *page)
         }
 }
 
-/*
- * Isolate one page from the LRU lists.
- *
- * - zone->lru_lock must be held
- */
-static inline int __isolate_lru_page(struct page *page)
-{
-        if (unlikely(!TestClearPageLRU(page)))
-                return 0;
-
-        if (get_page_testone(page)) {
-                /*
-                 * It is being freed elsewhere
-                 */
-                __put_page(page);
-                SetPageLRU(page);
-                return -ENOENT;
-        }
-
-        return 1;
-}
diff --git a/include/linux/swap.h b/include/linux/swap.h
index e92054d6530b..d01f7efb0f2c 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -167,6 +167,7 @@ extern void FASTCALL(lru_cache_add_active(struct page *));
 extern void FASTCALL(activate_page(struct page *));
 extern void FASTCALL(mark_page_accessed(struct page *));
 extern void lru_add_drain(void);
+extern int lru_add_drain_all(void);
 extern int rotate_reclaimable_page(struct page *page);
 extern void swap_setup(void);