slub: Switch per cpu partial page support off for debugging

Eric saw an issue with accounting of slabs during validation. Its not
possible to determine accurately how many per cpu partial slabs exist at
any time so this switches off per cpu partial pages during debug.
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

mm/slub.c

@@ -3028,7 +3028,9 @@ static int kmem_cache_open(struct kmem_cache *s,
 	 *    per node list when we run out of per cpu objects. We only fetch 50%
 	 *    to keep some capacity around for frees.
 	 */
-	if (s->size >= PAGE_SIZE)
+	if (kmem_cache_debug(s))
+		s->cpu_partial = 0;
+	else if (s->size >= PAGE_SIZE)
 		s->cpu_partial = 2;
 	else if (s->size >= 1024)
 		s->cpu_partial = 6;