Merge tag 'slab-for-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab fixes from Vlastimil Babka:

 - Fixes for several corner cases in error paths and debugging options,
   related to the new kmalloc_nolock() functionality (Kuniyuki Iwashima,
   Ran Xiaokai)

* tag 'slab-for-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  slub: Don't call lockdep_unregister_key() for immature kmem_cache.
  slab: Fix using this_cpu_ptr() in preemptible context
  slab: Add allow_spin check to eliminate kmemleak warnings

Author: torvalds

mm/slub.c

@@ -2152,7 +2152,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 		return 0;
 	}
 
-	kmemleak_not_leak(vec);
+	if (allow_spin)
+		kmemleak_not_leak(vec);
 	return 0;
 }
 
@@ -6431,17 +6432,24 @@ static void free_deferred_objects(struct irq_work *work)
 
 static void defer_free(struct kmem_cache *s, void *head)
 {
-	struct defer_free *df = this_cpu_ptr(&defer_free_objects);
+	struct defer_free *df;
+
+	guard(preempt)();
 
+	df = this_cpu_ptr(&defer_free_objects);
 	if (llist_add(head + s->offset, &df->objects))
 		irq_work_queue(&df->work);
 }
 
 static void defer_deactivate_slab(struct slab *slab, void *flush_freelist)
 {
-	struct defer_free *df = this_cpu_ptr(&defer_free_objects);
+	struct defer_free *df;
 
 	slab->flush_freelist = flush_freelist;
+
+	guard(preempt)();
+
+	df = this_cpu_ptr(&defer_free_objects);
 	if (llist_add(&slab->llnode, &df->slabs))
 		irq_work_queue(&df->work);
 }
@@ -7693,7 +7701,8 @@ void __kmem_cache_release(struct kmem_cache *s)
 		pcs_destroy(s);
 #ifndef CONFIG_SLUB_TINY
 #ifdef CONFIG_PREEMPT_RT
-	lockdep_unregister_key(&s->lock_key);
+	if (s->cpu_slab)
+		lockdep_unregister_key(&s->lock_key);
 #endif
 	free_percpu(s->cpu_slab);
 #endif