Re: [PATCH] cxl/memdev: fix deadlock in cxl_memdev_autoremove() on attach failure

[Gregory Price <gourry@gourry.net>]

On Tue, Feb 10, 2026 at 01:44:06PM -0600, Ira Weiny wrote:
> Gregory Price wrote:
> > 
> > diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> > index af3d0cc65138..c0de767b24fb 100644
> > --- a/drivers/cxl/core/memdev.c
> > +++ b/drivers/cxl/core/memdev.c
> > @@ -1098,19 +1098,22 @@ static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd)
> >  	 * return. Note that failure here could be the result of a race to
> >  	 * teardown the CXL port topology. I.e. cxl_mem_probe() could have
> >  	 * succeeded and then cxl_mem unbound before the lock is acquired.
> > +	 *
> > +	 * Check under device_lock but unregister outside of it, as
> > +	 * cxl_memdev_unregister() will also take the device lock.
> >  	 */
> > -	guard(device)(&cxlmd->dev);
> > -	if (cxlmd->attach && !cxlmd->dev.driver) {
> > -		cxl_memdev_unregister(cxlmd);
> > -		return ERR_PTR(-ENXIO);
> > +	scoped_guard(device, &cxlmd->dev) {
> > +		if (cxlmd->attach && !cxlmd->dev.driver)
> > +			break;
> > +
> > +		rc = devm_add_action_or_reset(cxlmd->cxlds->dev,
> > +					      cxl_memdev_unregister, cxlmd);
> 
> This kind of threw me...  Won't this deadlock if
> devm_add_action_or_reset() fails as well?
> 
> Need to use devm_add_action() and drop out of the guard on failure.
> 

lol i pointed out that this patch was a claude recommendation on the
initial report - didn't look to hard because it fixed this specific
deadlock with:

	if (cxlmd->attach && !cxlmd->dev.driver)
		break;

so yeah, easy enough to fixup.

I can either v2 or Dave if you want to just make the oneline change
before pull let me know

~Gregory