Re: PATCH V4 0/5 nvme-pci: fixes on nvme_timeout and nvme_dev_disable
From: Ming Lei
Date: Wed Apr 18 2018 - 22:28:06 EST
On Thu, Apr 19, 2018 at 09:51:16AM +0800, jianchao.wang wrote:
> Hi Ming
> Thanks for your kindly response.
> On 04/18/2018 11:40 PM, Ming Lei wrote:
> >> Regarding to this patchset, it is mainly to fix the dependency between
> >> nvme_timeout and nvme_dev_disable, as your can see:
> >> nvme_timeout will invoke nvme_dev_disable, and nvme_dev_disable have to
> >> depend on nvme_timeout when controller no response.
> > Do you mean nvme_disable_io_queues()? If yes, this one has been handled
> > by wait_for_completion_io_timeout() already, and looks the block timeout
> > can be disabled simply. Or are there others?
> Here is one possible scenario currently
> nvme_dev_disable // hold shutdown_lock nvme_timeout
> -> nvme_set_host_mem -> nvme_dev_disable
> -> nvme_submit_sync_cmd -> try to require shutdown_lock
> -> __nvme_submit_sync_cmd
> -> blk_execute_rq
> //if sysctl_hung_task_timeout_secs == 0
> -> wait_for_completion_io
> And maybe nvme_dev_disable need to issue other commands in the future.
OK, thanks for sharing this one, for now I think it might need to be
handled by wait_for_completion_io_timeout() for working around this issue.
> Even if we could fix these kind of issues as nvme_disable_io_queues,
> it is still a risk I think.
Yeah, I can't agree more, that is why I think the nvme time/eh code should
be refactored, and solve the current issues in a more clean/maintainable