mm: add gfp mask checking for __get_free_pages()

__get_free_pages() with __GFP_HIGHMEM is not safe because the return
address cannot represent a highmem page.  get_zeroed_page() already has
such a debug checking.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index afda8fd..81926c7 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1922,31 +1922,25 @@ EXPORT_SYMBOL(__alloc_pages_nodemask);
  */
 unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
 {
-       struct page * page;
+       struct page *page;
+
+       /*
+        * __get_free_pages() returns a 32-bit address, which cannot represent
+        * a highmem page
+        */
+       VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
+
        page = alloc_pages(gfp_mask, order);
        if (!page)
                return 0;
        return (unsigned long) page_address(page);
 }
-
 EXPORT_SYMBOL(__get_free_pages);
 
 unsigned long get_zeroed_page(gfp_t gfp_mask)
 {
-       struct page * page;
-
-       /*
-        * get_zeroed_page() returns a 32-bit address, which cannot represent
-        * a highmem page
-        */
-       VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
-
-       page = alloc_pages(gfp_mask | __GFP_ZERO, 0);
-       if (page)
-               return (unsigned long) page_address(page);
-       return 0;
+       return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
 }
-
 EXPORT_SYMBOL(get_zeroed_page);
 
 void __pagevec_free(struct pagevec *pvec)