Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2007-04-12 14:35:11.000000000 +1000
+++ linux-2.6/mm/slob.c	2007-05-09 11:01:09.000000000 +1000
@@ -35,6 +35,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/timer.h>
+#include <linux/rcupdate.h>
 
 struct slob_block {
 	int units;
@@ -53,6 +54,11 @@
 };
 typedef struct bigblock bigblock_t;
 
+struct slob_rcu {
+	struct rcu_head rcu_head;
+	struct kmem_cache *c;
+};
+
 static slob_t arena = { .next = &arena, .units = 1 };
 static slob_t *slobfree = &arena;
 static bigblock_t *bigblocks;
@@ -242,6 +248,7 @@
 
 struct kmem_cache {
 	unsigned int size, align;
+	unsigned long flags;
 	const char *name;
 	void (*ctor)(void *, struct kmem_cache *, unsigned long);
 	void (*dtor)(void *, struct kmem_cache *, unsigned long);
@@ -259,6 +266,11 @@
 	if (c) {
 		c->name = name;
 		c->size = size;
+		if (flags & SLAB_DESTROY_BY_RCU) {
+			/* leave room for rcu footer at the end of object */
+			c->size += sizeof(struct slob_rcu);
+		}
+		c->flags = flags;
 		c->ctor = ctor;
 		c->dtor = dtor;
 		/* ignore alignment unless it's forced */
@@ -281,9 +293,9 @@
 {
 	void *b;
 
-	if (c->size < PAGE_SIZE)
+	if (c->size < PAGE_SIZE) {
 		b = slob_alloc(c->size, flags, c->align);
-	else
+	} else
 		b = (void *)__get_free_pages(flags, find_order(c->size));
 
 	if (c->ctor)
@@ -303,7 +315,7 @@
 }
 EXPORT_SYMBOL(kmem_cache_zalloc);
 
-void kmem_cache_free(struct kmem_cache *c, void *b)
+static void __kmem_cache_free(struct kmem_cache *c, void *b)
 {
 	if (c->dtor)
 		c->dtor(b, c, 0);
@@ -313,6 +325,25 @@
 	else
 		free_pages((unsigned long)b, find_order(c->size));
 }
+
+static void kmem_rcu_free(struct rcu_head *head)
+{
+	struct slob_rcu *slob_rcu = (struct slob_rcu *)head;
+	void *b = (void *)slob_rcu - slob_rcu->c->size;
+
+	__kmem_cache_free(b, slob_rcu->c);
+}
+
+void kmem_cache_free(struct kmem_cache *c, void *b)
+{
+	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
+		struct slob_rcu *slob_rcu;
+		slob_rcu = b + c->size;;
+		slob_rcu->c = c;
+		call_rcu(&slob_rcu->rcu_head, kmem_rcu_free);
+	} else
+		__kmem_cache_free(b, c);
+}
 EXPORT_SYMBOL(kmem_cache_free);
 
 unsigned int kmem_cache_size(struct kmem_cache *c)
Index: linux-2.6/init/Kconfig
===================================================================
--- linux-2.6.orig/init/Kconfig	2007-04-12 14:35:11.000000000 +1000
+++ linux-2.6/init/Kconfig	2007-05-09 09:11:14.000000000 +1000
@@ -476,7 +476,7 @@
 
 config SLAB
 	default y
-	bool "Use full SLAB allocator" if (EMBEDDED && !SMP && !SPARSEMEM)
+	bool "Use full SLAB allocator" if (EMBEDDED && !SPARSEMEM)
 	help
 	  Disabling this replaces the advanced SLAB allocator and
 	  kmalloc support with the drastically simpler SLOB allocator.