On Mon, Jul 17, 2017 at 01:30:00PM +0300, Tomi Sarvela wrote:

First, tested that next-20170717 still triggers the problem when no extra
options given. Adding scsi_mod.use_blk_mq=0 makes tests work.

Then I tried with sd.diff patched next-20170717. Works (still) with
use_blk_mq=0. Also works when no options given, so this patch avoids the
hang when using the new block-mq.

These tests on generic Haswell 4790K desktop machine.

Thanks Tomi,

this seems to confirm it's runtime PM related, although I don't
really understand why that's an issue.  Let me spin up an implementation
of RQF_PM for blk-mq and give it to you for testing.