On Mon, Jul 04, 2022 at 02:51:44PM +0200, Christoph Hellwig wrote: > @@ -115,12 +116,15 @@ EXPORT_SYMBOL(mdev_unregister_parent); > static void mdev_device_release(struct device *dev) > { > struct mdev_device *mdev = to_mdev_device(dev); > + struct mdev_parent *parent = mdev->type->parent; > > /* Pairs with the get in mdev_device_create() */ > kobject_put(&mdev->type->kobj); > > mutex_lock(&mdev_list_lock); > list_del(&mdev->next); > + if (!parent->mdev_driver->get_available) > + parent->available_instances++; > mutex_unlock(&mdev_list_lock); I think the kobject_put() needs to be after this reference to parent because mdev_type_release() will: put_device(type->parent->dev); Which is potentially the last reference holding dev, and thus parent, at this moment. Jason