Re: [PATCH V3 0/3] Ensure ordered namespace registration during async scan

[Keith Busch <kbusch@kernel.org>]

On Wed, Feb 25, 2026 at 05:12:00PM +0100, Maurizio Lombardi wrote:
> The NVMe fully asynchronous namespace scanning introduced in
> commit 4e893ca81170 ("nvme-core: scan namespaces asynchronously")
> significantly improved discovery times. However, it also introduced
> non-deterministic ordering for namespace registration.
>
> While kernel device names (/dev/nvmeXnY) are not guaranteed to be stable
> across reboots, this unpredictable ordering has caused considerable user
> confusion and has been perceived as a regression, leading to multiple bug
> reports.

The nvme-pci driver also probes the controllers asynchronously, which
can also create non-determinisitic names. Is that part not a problem?

Just on the suffix part of the namespace's block handle, I have a
potential alternate suggestion here. The instance names pulled from the
ida guarantee we'll always have unique names for the lifetime of the
backing kobject. I introduced that a while ago, but I'm testing this out
now and it seems kobject_del is sufficient to reuse that name. The
driver already did that to all the objects when deleting the namespace,
so there doesn't appear to be a reason to wait for the final
kobject_put.

What I'm saying is I may have been mistaken about the naming collision
issues and we can just use the head's ns_id to get a consistent and
meaningful name based off the backing namespaces. There's some unlikely
races with multipath at the moment if we did use ns_id, but I think
they're all fixable.