Re: [PATCH v6 09/10] dax/kmem: add sysfs interface for atomic whole-device hotplug

[Gregory Price <gourry@gourry.net>]

On Thu, Jul 09, 2026 at 04:57:30PM -0700, Dan Williams (nvidia) wrote:
> Gregory Price wrote:
> > > So the "unknown" case does not need to be here.
> > >
> > 
> > mhp_online_type_to_str can technically return NULL, seems better to not
> > just let a NULL dereference sit latent even if we can visually tell it
> > can't happen today?
> 
> Oh, makes sense I was thinking "unknown" was only a result of the
> drvdata missing case.
> 
> > > > +	if (dax_kmem_state_is_online(data->state)) {
> > > > +		dev_warn(dev, "Hotplug regions stuck online until reboot\n");
> > > 
> > > I like that the BUG() is avoided, but I think these should stay
> > > dev_err() given the severity.
> > > 
> > 
> > I had to go back to calling remove_memory() by default given different
> > feedback, but I think if anything I will just modify the BUG() to a
> > WARN() and call it a day.
> 
> ack.

Ah, you know, on second look - DAX could never reach this BUG() in the
first place.  I think this was a hold-over from when i was originally
refactoring and trying to figure out the right path.

If there's a desire to soften these BUG() to WARN(), i can submit that
separately, but i will close this all out with some comment updates.