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/kernel/kexec.c b/kernel/kexec.c
index c0613f7..b55045b 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -816,7 +816,7 @@
 
 		ptr = kmap(page);
 		/* Start with a clear page */
-		memset(ptr, 0, PAGE_SIZE);
+		clear_page(ptr);
 		ptr += maddr & ~PAGE_MASK;
 		mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
 		if (mchunk > mbytes)