On Tue, Jan 09, 2018 at 09:41:03PM -0500, Mike Snitzer wrote: > Since I can remember DM has forced the block layer to allow the > allocation and initialization of the request_queue to be distinct > operations. Reason for this was block/genhd.c:add_disk() has required > that the request_queue (and associated bdi) be tied to the gendisk > before add_disk() is called -- because add_disk() also deals with > exposing the request_queue via blk_register_queue(). Hmm. I don't even know how that could be safe given that the disk is live and visible to userspace once added..