int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
{
	if (unlikely(bio->bi_css))
		return -EBUSY;
	css_get(blkcg_css);
	bio->bi_css = blkcg_css;
	return 0;
}

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.