Merge remote-tracking branch 'lsk/v3.10/topic/gator' into linux-linaro-lsk

[firefly-linux-kernel-4.4.55.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e0c8528a41a4d4a278fe736a46341755d46c5479..a9a48309f0458aa8faf408dc06edf9a623d9c5c4 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -361,8 +361,18 @@ static inline void compound_unlock_irqrestore(struct page *page,
 
 static inline struct page *compound_head(struct page *page)
 {
-       if (unlikely(PageTail(page)))
-               return page->first_page;
+       if (unlikely(PageTail(page))) {
+               struct page *head = page->first_page;
+
+               /*
+                * page->first_page may be a dangling pointer to an old
+                * compound page, so recheck that it is still a tail
+                * page before returning.
+                */
+               smp_rmb();
+               if (likely(PageTail(page)))
+                       return head;
+       }
        return page;
 }
 
@@ -766,11 +776,14 @@ static __always_inline void *lowmem_page_address(const struct page *page)
 #endif
 
 #if defined(WANT_PAGE_VIRTUAL)
-#define page_address(page) ((page)->virtual)
-#define set_page_address(page, address)                        \
-       do {                                            \
-               (page)->virtual = (address);            \
-       } while(0)
+static inline void *page_address(const struct page *page)
+{
+       return page->virtual;
+}
+static inline void set_page_address(struct page *page, void *address)
+{
+       page->virtual = address;
+}
 #define page_address_init()  do { } while(0)
 #endif