slub: Allow removal of slab caches during boot

If a slab cache is removed before we have setup sysfs then simply skip over
the sysfs handling.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Roland Dreier <rdreier@cisco.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

mm/slub.c

@@ -4507,6 +4507,13 @@ static int sysfs_slab_add(struct kmem_cache *s)
 
 static void sysfs_slab_remove(struct kmem_cache *s)
 {
+	if (slab_state < SYSFS)
+		/*
+		 * Sysfs has not been setup yet so no need to remove the
+		 * cache from sysfs.
+		 */
+		return;
+
 	kobject_uevent(&s->kobj, KOBJ_REMOVE);
 	kobject_del(&s->kobj);
 	kobject_put(&s->kobj);