1 files changed, 106 insertions, 0 deletions
diff --git a/mm/shrinker.c b/mm/shrinker.c
index a16cd448b924..d1032a4d5684 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -550,6 +550,112 @@ out:
 	return freed;
 }
 
+struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...)
+{
+	struct shrinker *shrinker;
+	unsigned int size;
+	va_list ap;
+	int err;
+
+	shrinker = kzalloc(sizeof(struct shrinker), GFP_KERNEL);
+	if (!shrinker)
+		return NULL;
+
+	va_start(ap, fmt);
+	err = shrinker_debugfs_name_alloc(shrinker, fmt, ap);
+	va_end(ap);
+	if (err)
+		goto err_name;
+
+	shrinker->flags = flags | SHRINKER_ALLOCATED;
+	shrinker->seeks = DEFAULT_SEEKS;
+
+	if (flags & SHRINKER_MEMCG_AWARE) {
+		err = prealloc_memcg_shrinker(shrinker);
+		if (err == -ENOSYS) {
+			/* Memcg is not supported, fallback to non-memcg-aware shrinker. */
+			shrinker->flags &= ~SHRINKER_MEMCG_AWARE;
+			goto non_memcg;
+		}
+
+		if (err)
+			goto err_flags;
+
+		return shrinker;
+	}
+
+non_memcg:
+	/*
+	 * The nr_deferred is available on per memcg level for memcg aware
+	 * shrinkers, so only allocate nr_deferred in the following cases:
+	 *  - non-memcg-aware shrinkers
+	 *  - !CONFIG_MEMCG
+	 *  - memcg is disabled by kernel command line
+	 */
+	size = sizeof(*shrinker->nr_deferred);
+	if (flags & SHRINKER_NUMA_AWARE)
+		size *= nr_node_ids;
+
+	shrinker->nr_deferred = kzalloc(size, GFP_KERNEL);
+	if (!shrinker->nr_deferred)
+		goto err_flags;
+
+	return shrinker;
+
+err_flags:
+	shrinker_debugfs_name_free(shrinker);
+err_name:
+	kfree(shrinker);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(shrinker_alloc);
+
+void shrinker_register(struct shrinker *shrinker)
+{
+	if (unlikely(!(shrinker->flags & SHRINKER_ALLOCATED))) {
+		pr_warn("Must use shrinker_alloc() to dynamically allocate the shrinker");
+		return;
+	}
+
+	down_write(&shrinker_rwsem);
+	list_add_tail(&shrinker->list, &shrinker_list);
+	shrinker->flags |= SHRINKER_REGISTERED;
+	shrinker_debugfs_add(shrinker);
+	up_write(&shrinker_rwsem);
+}
+EXPORT_SYMBOL_GPL(shrinker_register);
+
+void shrinker_free(struct shrinker *shrinker)
+{
+	struct dentry *debugfs_entry = NULL;
+	int debugfs_id;
+
+	if (!shrinker)
+		return;
+
+	down_write(&shrinker_rwsem);
+	if (shrinker->flags & SHRINKER_REGISTERED) {
+		list_del(&shrinker->list);
+		debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
+		shrinker->flags &= ~SHRINKER_REGISTERED;
+	}
+
+	shrinker_debugfs_name_free(shrinker);
+
+	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+		unregister_memcg_shrinker(shrinker);
+	up_write(&shrinker_rwsem);
+
+	if (debugfs_entry)
+		shrinker_debugfs_remove(debugfs_entry, debugfs_id);
+
+	kfree(shrinker->nr_deferred);
+	shrinker->nr_deferred = NULL;
+
+	kfree(shrinker);
+}
+EXPORT_SYMBOL_GPL(shrinker_free);
+
 /*
  * Add a shrinker callback to be called from the vm.
  */