Add additional debugging to detect wrong node slabs

This patch adds some stack dumps if the slab logic is processing
slab blocks from the wrong node. This is necessary in order to detect
situations as encountered by Petr.

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

Index: linux-2.6.14-rc2/mm/slab.c
===================================================================
--- linux-2.6.14-rc2.orig/mm/slab.c	2005-09-27 13:22:30.000000000 -0700
+++ linux-2.6.14-rc2/mm/slab.c	2005-09-28 15:46:31.000000000 -0700
@@ -2421,6 +2421,7 @@ retry:
 			next = slab_bufctl(slabp)[slabp->free];
 #if DEBUG
 			slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE;
+			WARN_ON(numa_node_id() != slabp->nodeid);
 #endif
 		       	slabp->free = next;
 		}
@@ -2635,8 +2636,10 @@ static void free_block(kmem_cache_t *cac
 		check_spinlock_acquired_node(cachep, node);
 		check_slabp(cachep, slabp);
 
-
 #if DEBUG
+		/* Verify that the slab belongs to the intended node */
+		WARN_ON(slabp->nodeid != node);
+
 		if (slab_bufctl(slabp)[objnr] != BUFCTL_FREE) {
 			printk(KERN_ERR "slab: double free detected in cache "
 					"'%s', objp %p\n", cachep->name, objp);