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.
I can confirm that this patch fixes the kernel panics I've seen.
For what it's worth, the USB hotplugging issues didn't
re-surface, either. Thanks!
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Patrick Steinhardt <ps@xxxxxx>
> Cc: Bart Van Assche <Bart.VanAssche@xxxxxxx>
> Cc: Tomas Janousek <tomi@xxxxxxx>
> Cc: Przemek Socha <soprwa@xxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> block/blk-core.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 03a4ea93a5f3..090b782df129 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -3769,9 +3769,11 @@ 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;
> --
> 2.9.5
>
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