Re: [PATCH] drm/xe: Fix fault on fd close when wedged

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Dec 11, 2024 at 10:26:15PM -0600, Lucas De Marchi wrote:
> On Wed, Dec 11, 2024 at 07:51:57PM -0800, Matthew Brost wrote:
> > On Wed, Dec 11, 2024 at 02:53:32PM -0800, Lucas De Marchi wrote:
> > > If device is wedged, the final run ticks update for the client should be
> > > skipped as it's already unmapped. Fix this pagefault when forcing a
> > 
> > Where does exec queue get unmapped on wedging a device?
> 
> it's the lrc we are trying to read: lrc->bo, with offset == timestamp.
> 
> I thought it was part of the the xe_gt_declare_wedged(), but I'm not
> following what triggers it - the only thing that should trigger that
> would be the xe_lrc_put() and the refcount reaching 0. Something is not
> adding up here, I will have to trace the destroy to see what's going on.
> 

Quick reached the same conclusion - accessing the LRC BO should be safe
until the final put, hence my question. It does appear something else
weird is going on here.

Matt

> Lucas De Marchi