Slab: Do not fallback to nodes that have not been bootstrapped yet

The zonelist may contain zones of nodes that have not been bootstrapped
and we will oops if we try to allocate from nodes. So check if the node
information for the slab and the node have been setup before attempting
an allocation. If it has not been setup then skip that zone.

Usually we will not encounter this situation since the slab bootstrap
code avoids falling back but we seem to have a special needs for
pppc.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.19-rc2-mm1/mm/slab.c
===================================================================
--- linux-2.6.19-rc2-mm1.orig/mm/slab.c	2006-10-20 12:39:02.000000000 -0500
+++ linux-2.6.19-rc2-mm1/mm/slab.c	2006-10-20 12:41:04.137684581 -0500
@@ -3160,12 +3160,15 @@ void *fallback_alloc(struct kmem_cache *
 	struct zone **z;
 	void *obj = NULL;
 
-	for (z = zonelist->zones; *z && !obj; z++)
+	for (z = zonelist->zones; *z && !obj; z++) {
+		int nid = zone_to_nid(*z);
+
 		if (zone_idx(*z) <= ZONE_NORMAL &&
-				cpuset_zone_allowed(*z, flags))
+				cpuset_zone_allowed(*z, flags) &&
+				cache->nodelists[nid])
 			obj = __cache_alloc_node(cache,
-					flags | __GFP_THISNODE,
-					zone_to_nid(*z));
+					flags | __GFP_THISNODE, nid);
+	}
 	return obj;
 }