From: Ming Lei <ming.lei@redhat.com>
Subject: block: really disable runtime-pm for blk-mq
Date: Mon, 30 Jul 2018 20:02:19 +0800
Origin: https://patchwork.kernel.org/patch/10548975/
Bug-Debian: https://bugs.debian.org/904441

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.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Patrick Steinhardt <ps@pks.im>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: Tomas Janousek <tomi@nomi.cz>
Cc: Przemek Socha <soprwa@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3784,9 +3784,11 @@ EXPORT_SYMBOL(blk_finish_plug);
  */
 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
 {
-	/* not support for RQF_PM and ->rpm_status in blk-mq yet */
-	if (q->mq_ops)
+	/* Don't enable runtime PM for blk-mq until it is ready */
+	if (q->mq_ops) {
+		pm_runtime_disable(dev);
 		return;
+	}
 
 	q->dev = dev;
 	q->rpm_status = RPM_ACTIVE;