t is done
- * before the return from the function. Therefore for any single-argument
- * call that will result in a kfree() to a cache that is to be destroyed
- * during module exit, it is developer's responsibility to ensure that all
- * such calls have returned before the call to kmem_cache_destroy().
- */
-void kvfree_rcu_barrier(void)
+static inline void __kvfree_rcu_barrier(void)
 {
 	struct kfree_rcu_cpu_work *krwp;
 	struct kfree_rcu_cpu *krcp;
 	bool queued;
 	int i, cpu;
 
-	flush_all_rcu_sheaves();
-
 	/*
 	 * Firstly we detach objects and queue them over an RCU-batch
 	 * for all CPUs. Finally queued works are flushed for each CPU.
@@ -2119,8 +2107,43 @@ void kvfree_rcu_barrier(void)
 		}
 	}
 }
+
+/**
+ * kvfree_rcu_barrier - Wait until all in-flight kvfree_rcu() complete.
+ *
+ * Note that a single argument of kvfree_rcu() call has a slow path that
+ * triggers synchronize_rcu() following by freeing a pointer. It is done
+ * before the return from the function. Therefore for any single-argument
+ * call that will result in a kfree() to a cache that is to be destroyed
+ * during module exit, it is developer's responsibility to ensure that all
+ * such calls have returned before the call to kmem_cache_destroy().
+ */
+void kvfree_rcu_barrier(void)
+{
+	flush_all_rcu_sheaves();
+	__kvfree_rcu_barrier();
+}
 EXPORT_SYMBOL_GPL(kvfree_rcu_barrier);
 
+/**
+ * kvfree_rcu_barrier_on_cache - Wait for in-flight kvfree_rcu() calls on a
+ *                               specific slab cache.
+ * @s: slab cache to wait for
+ *
+ * See the description of kvfree_rcu_barrier() for details.
+ */
+void kvfree_rcu_barrier_on_cache(struct kmem_cache *s)
+{
+	if (s->cpu_sheaves)
+		flush_rcu_sheaves_on_cache(s);
+	/*
+	 * TODO: Introduce a version of __kvfree_rcu_barrier() that works
+	 * on a specific slab cache.
+	 */
+	__kvfree_rcu_barrier();
+}
+EXPORT_SYMBOL_GPL(kvfree_rcu_barrier_on_cache);
+
 static unsigned long
 kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 {
@@ -2216,4 +2239,3 @@ void __init kvfree_rcu_init(void)
 }
 
 #endif /* CONFIG_KVFREE_RCU_BATCHED */
-
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4118,42 +4118,47 @@ static void flush_rcu_sheaf(struct work_
 
 
 /* needed for kvfree_rcu_barrier() */
-void flush_all_rcu_sheaves(void)
+void flush_rcu_sheaves_on_cache(struct kmem_cache *s)
 {
 	struct slub_flush_work *sfw;
-	struct kmem_cache *s;
 	unsigned int cpu;
 
+	mutex_lock(&flush_lock);
+
+	for_each_online_cpu(cpu) {
+		sfw = &per_cpu(slub_flush, cpu);
+
+		/*
+		 * we don't check if rcu_free sheaf exists - racing
+		 * __kfree_rcu_sheaf() might have just removed it.
+		 * by executing flush_rcu_sheaf() on the cpu we make
+		 * sure the __kfree_rcu_sheaf() finished its call_rcu()
+		 */
+
+		INIT_WORK(&sfw->work, flush_rcu_sheaf);
+		sfw->s = s;
+		queue_work_on(cpu, flushwq, &sfw->work);
+	}
+
+	for_each_online_cpu(cpu) {
+		sfw = &per_cpu(slub_flush, cpu);
+		flush_work(&sfw->work);
+	}
+
+	mutex_unlock(&flush_lock);
+}
+
+void flush_all_rcu_sheaves(void)
+{
+	struct kmem_cache *s;
+
 	cpus_read_lock();
 	mutex_lock(&slab_mutex);
 
 	list_for_each_entry(s, &slab_caches, list) {
 		if (!s->cpu_sheaves)
 			continue;
-
-		mutex_lock(&flush_lock);
-
-		for_each_online_cpu(cpu) {
-			sfw = &per_cpu(slub_flush, cpu);
-
-			/*
-			 * we don't check if rcu_free sheaf exists - racing
-			 * __kfree_rcu_sheaf() might have just removed it.
-			 * by executing flush_rcu_sheaf() on the cpu we make
-			 * sure the __kfree_rcu_sheaf() finished its call_rcu()
-			 */
-
-			INIT_WORK(&sfw->work, flush_rcu_sheaf);
-			sfw->s = s;
-			queue_work_on(cpu, flushwq, &sfw->work);
-		}
-
-		for_each_online_cpu(cpu) {
-			sfw = &per_cpu(slub_flush, cpu);
-			flush_work(&sfw->work);
-		}
-
-		mutex_unlock(&flush_lock);
+		flush_rcu_sheaves_on_cache(s);
 	}
 
 	mutex_unlock(&slab_mutex);[PATCH 6.18 275/430] mm/slab: introduce kvfree_rcu_barrier_on_cache() for cache destructionGreg Kroah-Hartman <gregkh@linuxfoundation.org> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefined undefined