[PATCH 2/4] pfnmap: cow_user_page needs mask

From: Hugh Dickins (hugh_at_veritas.com)
Date: 11/29/05

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    Date:	Tue, 29 Nov 2005 16:53:56 +0000 (GMT)
To: Linus Torvalds <torvalds@osdl.org>

    The fault address to cow_user_page is not usually page aligned, so needs
    to be masked in the unusual case when that copies via the user address.

    Signed-off-by: Hugh Dickins <hugh@veritas.com> 

    ---
 mm/memory.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletion(-)
--- 2.6.15-rc3/mm/memory.c	2005-11-29 08:40:07.000000000 +0000
+++ linux/mm/memory.c	2005-11-29 15:59:34.000000000 +0000
@@ -1300,7 +1313,8 @@ static inline void cow_user_page(struct 
 	 */
 	if (unlikely(!src)) {
 		void *kaddr = kmap_atomic(dst, KM_USER0);
-		unsigned long left = __copy_from_user_inatomic(kaddr, (void __user *)va, PAGE_SIZE);
+		unsigned long left = __copy_from_user_inatomic(kaddr,
+			(void __user *)(va & PAGE_MASK), PAGE_SIZE);
 		if (left)
 			memset(kaddr, 0, PAGE_SIZE);
 		kunmap_atomic(kaddr, KM_USER0);
-
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