Re: [PATCH v3 2/2] cxl: Fix race of nvdimm_bus object when creating nvdimm objects

[Dave Jiang <dave.jiang@intel.com>]

On 2/23/26 3:18 PM, Gregory Price wrote:
> On Fri, Feb 13, 2026 at 03:40:38PM -0700, Dave Jiang wrote:
>> @@ -248,6 +262,19 @@ int devm_cxl_add_nvdimm(struct device *host, struct cxl_port *port,
>>  	if (!cxl_nvb)
>>  		return -ENODEV;
>>  
>> +	/*
>> +	 * Take the uport_dev lock to guard against race of nvdimm_bus object.
>> +	 * cxl_acpi_probe() registers the nvdimm_bus and is done under the
>> +	 * root port uport_dev lock.
>> +	 *
>> +	 * Take the cxl_nvb device lock to ensure that cxl_nvb driver is in a
>> +	 * consistent state. And the driver registers nvdimm_bus.
>> +	 */
>> +	guard(device)(cxl_nvb->port->uport_dev);
>> +	guard(device)(&cxl_nvb->dev);
>> +	if (!cxl_nvb->nvdimm_bus)
>> +		return -ENODEV;
>> +
> 
> I think this leaks the reference on cxl_nvb taken by 
> 
> 	devm_cxl_add_nvdimm()
> 		device_find_child()
> 
> Maybe:
>      if (!cxl_nvb->nvdimm_bus) {
>              rc = -ENODEV;
>              goto err_alloc;
>      }
> 
> 
> Reported-by: kreview-0811365

Thanks! I've fixed it up in place in cxl/fixes.

> 
> ~Gregory