use clear_page()/copy_page() in favor of memset()/memcpy() on whole pages

After all that's what they are intended for.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 861f798..02e48aa 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2080,7 +2080,7 @@
 		 * zeroes.
 		 */
 		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
-			memset(kaddr, 0, PAGE_SIZE);
+			clear_page(kaddr);
 		kunmap_atomic(kaddr, KM_USER0);
 		flush_dcache_page(dst);
 	} else