NVME regression in all kernels after 4.4.x for NVME in M2 slot for laptop?

[Keith Busch]

On Fri, Aug 05, 2016 at 12:03:23PM -0700, Marc MERLIN wrote:
> Would this patch make sense as being the reason why I can't S3 sleep
> anymore and would you have a test patch against 4.5, 4.6, or 4.7 I can
> try to see if it fixes the problem?

Hi Marc,

It might be blk-mq's hot cpu notifier is invoked during suspend and
waiting for nvme's queues to freeze, which may not happen if a request
is waiting on a stopped queue. The patch you biseceted doesn't
necessarilly fix that, but the window for when a request could get queued
like that was much shorter.

Assuming that is the problem, S3 suspends PCI hardware before IO
tasks. I'll see if I can reproduce on one of my machines and look into
a fix.

Thanks,
Keith