On Tue, Dec 20 2016, Paolo Valente wrote:

quoted

+	else
+		rq = __blk_mq_alloc_request(data, op);
+
+	if (rq) {
+		rq->elv.icq = NULL;
+		if (e && e->type->icq_cache)
+			blk_mq_sched_assign_ioc(q, rq, bio);

bfq needs rq->elv.icq to be consistent in bfq_get_request, but the
needed initialization seems to occur only after mq.get_request is
invoked.

Can you do it from get/put_rq_priv? The icq is assigned there. If not,
we can redo this part, not a big deal.

-- 
Jens Axboe