On Mon, Jul 30, 2018 at 08:02:19PM +0800, Ming Lei wrote:

Runtime PM isn't ready for blk-mq yet, and commit 765e40b675a9 ("block:
disable runtime-pm for blk-mq") tried to disable it. Unfortunately,
it can't take effect in that way since user space still can switch
it on via 'echo auto > /sys/block/sdN/device/power/control'.

This patch disables runtime-pm for blk-mq really by pm_runtime_disable()
and fixes all kinds of PM related kernel crash.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>