page-pipe: fix memory leak on error path

CID 996197 (#1 of 1): Resource leak (RESOURCE_LEAK)
8. leaked_storage: Variable ppb going out of scope leaks the storage it points to.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

page-pipe.c

@@ -17,6 +17,7 @@ static int page_pipe_grow(struct page_pipe *pp)
 		return -1;
 
 	if (pipe(ppb->p)) {
+		xfree(ppb);
 		pr_perror("Can't make pipe for page-pipe");
 		return -1;
 	}