On Fri, Sep 14, 2018 at 09:52:38AM +0800, Ming Lei wrote: > However, in previous discussion, it is strongly objected to use > per-driver/device .use_blk_mq switch, so not sure if this way can > be accepted. I don't like the per-driver switch as module_parameter at all and we should never do that. We had some exceptions for drivers to force blk_mq (e.g. virtio), and given that I don't think we'll solve the blk-mq runtime-pm issue for 4.19 and also don't want to revert the default I think this patch is the best compromise for 4.19, with a revert in 4.20 once we have runtime-pm for blk-mq. So: Acked-by: Christoph Hellwig <hch@xxxxxx>