xip: fix get_zeroed_page with __GFP_HIGHMEM

The use of get_zeroed_page() with __GFP_HIGHMEM is invalid.  Use
alloc_page() with __GFP_ZERO instead of invalid get_zeroed_page().

(This patch is only compile tested)

Cc: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Acked-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/filemap_xip.c

@@ -25,14 +25,15 @@ static struct page *__xip_sparse_page;
 static struct page *xip_sparse_page(void)
 {
 	if (!__xip_sparse_page) {
-		unsigned long zeroes = get_zeroed_page(GFP_HIGHUSER);
-		if (zeroes) {
+		struct page *page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
+
+		if (page) {
 			static DEFINE_SPINLOCK(xip_alloc_lock);
 			spin_lock(&xip_alloc_lock);
 			if (!__xip_sparse_page)
-				__xip_sparse_page = virt_to_page(zeroes);
+				__xip_sparse_page = page;
 			else
-				free_page(zeroes);
+				__free_page(page);
 			spin_unlock(&xip_alloc_lock);
 		}
 	}