Re: [PATCH 0/7] Fix a couple of wedge corner-case memory leaks

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

On Mon, Oct 13, 2025 at 04:24:57PM +0000, Stuart Summers wrote:
> Most of the patches in this series are just adding
> some debug hints to help track these down. I split
> these up in case we want to pick and choose which ones
> to include in the tree. I found them useful.
> 
> The main two interesting patches are the last two in the
> series which are fixing some corner cases when the
> driver becomes wedged in the middle of either communication
> with the DRM scheduler or in the event the GuC becomes
> unresponsive. In both of these cases there is a chance
> we could leak memory around the exec queue members
> like the LRC and the LRC BO. These patches fix those
> scenarios.
> 

Ok, I think I see the problem. I believe the correct approach is:

- Apply [1]

- Ensure all schedulers are not stopped in guc_submit_wedged_fini

- Clean up any lost H2G in guc_submit_wedged_fini similar to a GT reset

- Wait on all async scheduler work queue opertaions complete somewhere
  (this is part of VLK-80263, I was going to try to look at this part
  sometime this week). 

Matt

[1] https://patchwork.freedesktop.org/series/155417/

> v2: Address feedback from Matt:
>     - Let the DRM scheduler handle pausing/unpausing
>     - Still do the wait after scheduling disable/deregister
>       as with the previous patch, but skip the intermediate
>       software-based schedule disable using the "banned"
>       flag and instead just jump straight to the deregister
>       handling which will fully reset the queue state.
>       Note that for this case I am seeing a hardware failure
>       after submitting to GuC but before receiving the
>       response from GuC. So even if we wedge in this case
>       (monitoring the hardware state change), the queue
>       itself is not wedged because of the active GuC
>       submission (CT is not stalled at that point).
> 
> Stuart Summers (7):
>   drm/xe: Add additional trace points for LRCs
>   drm/xe: Add a trace point for VM close
>   drm/xe: Add the BO pointer info to the BO trace
>   drm/xe: Add new exec queue trace points
>   drm/xe: Correct migration VM teardown order
>   drm/xe: Don't block messages to the GPU scheduler
>   drm/xe: Check for GuC responses on disabling scheduling
> 
>  drivers/gpu/drm/xe/xe_exec_queue.c    |  4 +++
>  drivers/gpu/drm/xe/xe_gpu_scheduler.c |  6 +---
>  drivers/gpu/drm/xe/xe_guc_submit.c    | 24 ++++++++++++---
>  drivers/gpu/drm/xe/xe_lrc.c           |  4 +++
>  drivers/gpu/drm/xe/xe_lrc.h           |  3 ++
>  drivers/gpu/drm/xe/xe_migrate.c       |  2 +-
>  drivers/gpu/drm/xe/xe_trace.h         | 22 ++++++++++++--
>  drivers/gpu/drm/xe/xe_trace_bo.h      | 12 ++++++--
>  drivers/gpu/drm/xe/xe_trace_lrc.h     | 42 ++++++++++++++++++++++++++-
>  drivers/gpu/drm/xe/xe_vm.c            |  2 ++
>  10 files changed, 106 insertions(+), 15 deletions(-)
> 
> -- 
> 2.34.1
>