Handle unknown node (-1) in alloc_pages_node

Following kmalloc_node.

Needed for the next patch to return -1 for unknown nodes in x86-64.

Cc: clameter@engr.sgi.com
Cc: kiran@scalex86.org

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/include/linux/gfp.h
===================================================================
--- linux.orig/include/linux/gfp.h
+++ linux/include/linux/gfp.h
@@ -109,6 +109,10 @@ static inline struct page *alloc_pages_n
 	if (unlikely(order >= MAX_ORDER))
 		return NULL;
 
+	/* Unknown node is node 0 */
+	if (nid < 0)
+		nid = 0;
+
 	return __alloc_pages(gfp_mask, order,
 		NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
 }