slab fixes for 6.0-rc7

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Merge tag 'slab-for-6.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab fixes from Vlastimil Babka:

 - Fix a possible use-after-free in SLUB's kmem_cache removal,
   introduced in this cycle, by Feng Tang.

 - WQ_MEM_RECLAIM dependency fix for the workqueue-based cpu slab
   flushing introduced in 5.15, by Maurizio Lombardi.

 - Add missing KASAN hooks in two kmalloc entry paths, by Peter
   Collingbourne.

 - A BUG_ON() removal in SLUB's kmem_cache creation when allocation
   fails (too small to possibly happen in practice, syzbot used fault
   injection), by Chao Yu.

* tag 'slab-for-6.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context.
  mm/slab_common: fix possible double free of kmem_cache
  kasan: call kasan_malloc() from __kmalloc_*track_caller()
  mm/slub: fix to return errno if kmalloc() fails

mm/slab_common.c

@@ -475,6 +475,7 @@ void slab_kmem_cache_release(struct kmem_cache *s)
 void kmem_cache_destroy(struct kmem_cache *s)
 {
 	int refcnt;
+	bool rcu_set;
 
 	if (unlikely(!s) || !kasan_check_byte(s))
 		return;
@@ -482,6 +483,8 @@ void kmem_cache_destroy(struct kmem_cache *s)
 	cpus_read_lock();
 	mutex_lock(&slab_mutex);
 
+	rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU;
+
 	refcnt = --s->refcount;
 	if (refcnt)
 		goto out_unlock;
@@ -492,7 +495,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
 out_unlock:
 	mutex_unlock(&slab_mutex);
 	cpus_read_unlock();
-	if (!refcnt && !(s->flags & SLAB_TYPESAFE_BY_RCU))
+	if (!refcnt && !rcu_set)
 		kmem_cache_release(s);
 }
 EXPORT_SYMBOL(kmem_cache_destroy);

mm/slub.c

@@ -310,6 +310,11 @@ static inline void stat(const struct kmem_cache *s, enum stat_item si)
  */
 static nodemask_t slab_nodes;
 
+/*
+ * Workqueue used for flush_cpu_slab().
+ */
+static struct workqueue_struct *flushwq;
+
 /********************************************************************
  * 			Core slab cache functions
  *******************************************************************/
@@ -2730,7 +2735,7 @@ static void flush_all_cpus_locked(struct kmem_cache *s)
 		INIT_WORK(&sfw->work, flush_cpu_slab);
 		sfw->skip = false;
 		sfw->s = s;
-		schedule_work_on(cpu, &sfw->work);
+		queue_work_on(cpu, flushwq, &sfw->work);
 	}
 
 	for_each_online_cpu(cpu) {
@@ -4858,6 +4863,8 @@ void __init kmem_cache_init(void)
 
 void __init kmem_cache_init_late(void)
 {
+	flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0);
+	WARN_ON(!flushwq);
 }
 
 struct kmem_cache *
@@ -4926,6 +4933,8 @@ void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
 	/* Honor the call site pointer we received. */
 	trace_kmalloc(caller, ret, s, size, s->size, gfpflags);
 
+	ret = kasan_kmalloc(s, ret, size, gfpflags);
+
 	return ret;
 }
 EXPORT_SYMBOL(__kmalloc_track_caller);
@@ -4957,6 +4966,8 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
 	/* Honor the call site pointer we received. */
 	trace_kmalloc_node(caller, ret, s, size, s->size, gfpflags, node);
 
+	ret = kasan_kmalloc(s, ret, size, gfpflags);
+
 	return ret;
 }
 EXPORT_SYMBOL(__kmalloc_node_track_caller);
@@ -5890,7 +5901,8 @@ static char *create_unique_id(struct kmem_cache *s)
 	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
 	char *p = name;
 
-	BUG_ON(!name);
+	if (!name)
+		return ERR_PTR(-ENOMEM);
 
 	*p++ = ':';
 	/*
@@ -5948,6 +5960,8 @@ static int sysfs_slab_add(struct kmem_cache *s)
 		 * for the symlinks.
 		 */
 		name = create_unique_id(s);
+		if (IS_ERR(name))
+			return PTR_ERR(name);
 	}
 
 	s->kobj.kset = kset;