Re: [PATCH v2] cxl/region: Unregister the pmem region bridge on setup failure

[Guixin Liu <kanie@linux.alibaba.com>]

在 2026/8/13 05:42, Alison Schofield 写道:
> On Wed, Aug 12, 2026 at 02:10:43PM +0800, Guixin Liu wrote:
>
> About the subject line:
>
> Do we unregister the bridge or do we unregister the pmem
> region when the bridge is unboound?
>
Unregister the pmem region, sorry for the confusing description.
>> devm_cxl_add_pmem_region() publishes the cxl_pmem_region with device_add()
>> and only afterwards, under the nvdimm bridge's device lock, arranges for
>> its removal - and only if the bridge has a driver bound. If it does not,
>> the function sets -ENXIO and leaves through err_bridge, which drops the
>> reference this function took on the bridge and returns. The device that
>> was just added has no owner at that point: no device_del(), no
>> put_device(), and no devm action to do either later. The sibling failure,
>> a devm_add_action_or_reset() that cannot allocate, is already covered,
>> because devm_add_action_or_reset() runs cxlr_pmem_unregister() itself on
>> that path.
>>
>> An unbound bridge is a normal state, not an error state. The bridge is
>> unbound whenever cxl_pmem is unloaded or its device is detached through
>> sysfs, and a region can be probed in that window.
>>
>> The added device then stays in sysfs, along with the reference it holds on
>> the region, until the module is unloaded. cxlr->cxlr_pmem still points at
>> it, and worse, the name is still taken: a later probe of the same region
>> allocates a second cxl_pmem_region and fails in device_add() on the
>> duplicate "pmem_region%d", so once this has happened the region can no
>> longer be brought up at all.
> Is above an observed behavior?  ie can you reproduce this, apply
> the fix, see it go away?  That would be far more valuable than this
> excessive narration as proof of repair.
>
> More below...
I'm so sorry, I thought that we should add cleanup in
failure branch, but now I realize that this branch is never actually 
reached.

Please ignore this patch, sorry again.

Best Regards,
Guixin Liu