On Tue, Dec 11, 2018 at 11:19:22PM -0800, Sagi Grimberg wrote: >> So we need to make sure in the block layer or I/O submitter that >> REQ_HIPRI is only set if QUEUE_FLAG_POLL is supported. I think it would >> also help if we rename it to REQ_POLL to make this more obvious. > > It used to check for it, but was changed to look at nr_maps instead... > So I think this is a regression... blk_mq_map_queue looks at both QUEUE_FLAG_POLL and nr_maps for the queue selection, but that doesn't help with the problem that we should never pass poll requests through stacking devices.