Index: linux-2.6.21-rc1/mm/slub.c
===================================================================
--- linux-2.6.21-rc1.orig/mm/slub.c	2007-02-28 00:50:10.000000000 -0800
+++ linux-2.6.21-rc1/mm/slub.c	2007-02-28 08:02:48.000000000 -0800
@@ -67,9 +67,11 @@
  * Set of flags that will prevent slab merging
  */
 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-	SLAB_DESTROY_BY_RCU | SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
 	SLAB_TRACE)
 
+#define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_DESTROY_BY_RCU | \
+	SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | SLAB_SANITY)
+
 #ifndef ARCH_KMALLOC_MINALIGN
 #define ARCH_KMALLOC_MINALIGN sizeof(void *)
 #endif
@@ -297,17 +299,21 @@
 /*
  * Object layout:
  *
- * object
+ * object address
  * 		Bytes of the object to be managed.
- * object + objsize
- * 		Filler to reach word boundary. This is also used for redzoning.
- * object + inuse
- * 		Filler to reach required alignment boundary
- * object + size
+ * 		If the freepointer may overlay the object then the free
+ * 		pointer is the first word of the object.
+ * object + s->objsize
+ * 		Padding to reach word boundary. This is also used for Redzoning.
+ * 		Padding is extended to word size if Redzoning is enabled
+ * 		and objsize == inuse.
+ * object + s->inuse
+ * 		A. Free pointer (if we cannot overwrite object on free)
+ * 		B. Tracking data for SLAB_STORE_USER
+ * 		C. Padding to reach required alignment boundary
+ * object + s->size
  *
- * Object layouts can only be assured if the slabcache was not merged. If any
- * debug options are set then the slabcache will not be merged. If slabs were
- * merged then the objsize and inuse boundaries are to be ignored.
+ * If slabcaches are merged then the objsize and inuse boundaries are to be ignored.
  */
 static int check_object(struct kmem_cache *s, struct page *page,
 					void *object, int active)
@@ -1162,19 +1168,14 @@
 static int slub_min_order = 0;
 
 /*
- * Merge control. If this is set then no merging of slab caches into the
- * general caches will occur.
+ * Merge control. If this is set then no merging of slab caches will occur.
  */
 static int slub_nomerge = 0;
 
 /*
  * Debug settings:
- *
- * Run with with mininum sanity checks during slub development.
  */
-
-// static int slub_debug = 0;
-static int slub_debug = SLAB_SANITY;
+static int slub_debug = 0;
 
 static char *slub_debug_slabs = NULL;
 
@@ -1772,24 +1773,16 @@
 static struct kmem_cache *kmem_cache_dup(struct kmem_cache *s,
 				gfp_t flags, const char *name)
 {
-	char *x;
-
 	atomic_inc(&s->refcount);
-#if 0
 	down_write(&slabstat_sem);
 	if (!s->aliases)
 		s->aliases = kstrdup(name, flags);
 	else {
-		x = kmalloc(strlen(s->aliases) + strlen(name) + 1,
-						flags);
-		strcpy(x, s->aliases);
-		strcat(x, " ");
-		strcat(x, name);
-		kfree(s->aliases);
-		s->aliases = x;
+		char *x = s->aliases;
+		s->aliases = kasprintf(flags, "%s/%s", s->aliases, name);
+		kfree(x);
 	}
 	up_write(&slabstat_sem);
-#endif
 	return s;
 }
 
@@ -1824,6 +1817,9 @@
 		if (s->flags & SLUB_NEVER_MERGE)
 			continue;
 
+		if (((flags | slub_debug) & SLUB_MERGE_SAME) !=
+			(s->flags & SLUB_MERGE_SAME))
+				continue;
 		/*
 		 * Check if alignment is compatible.
 		 * Courtesy of Adrian Drzewiecki