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

[Hannes Reinecke <hare@suse.de>]

On 7/1/26 12:14 AM, Gregory Price wrote:
> On Tue, Jun 30, 2026 at 05:18:41PM -0400, Gregory Price wrote:
>> There is no atomic mechanism to offline and remove an entire
>> multi-block DAX kmem device.  This is presently done in two steps:
> 
> ... snip snip snip ...
> 
> Sashiko pointed out a false-positive, but adding a fixup patch
> here that adds additional consistency.
> 
> On total failure - release all resources.  This makes the sysfs
> interface consistent with the probe failure path.
> 

Speaking of which ...
With this patch we now have _two_ interfaces to do the same thing.
And both will be generating uevents.
Which is far from ideal (one could easily envision _conflicting_
udev rules, one set doing an 'online' on the old interface,
and another set doing an 'offline' on the new interface...)
Is there a way to not sending uevents for the old interface
or to make it configurable?
The old interface had the nasty side effect of generating
_tons_ of uevents during booting, and on larger machines we
even had seen udev acting as a fork-bomb during booting,
taking down the entire machine (we had to restrict udev
to 512 threads max to avoid that from happening).
So if we could disable uevents for the old interface
things would be _so_ much easier ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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