Re: [PATCH] drm/amdgpu/userq: serialize queue map against GPU reset

On 03-Aug-26 3:05 PM, Jesse Zhang wrote:
> Creating a user queue can race with a GPU reset. While recovery holds
> reset_domain->sem for write, MES is unresponsive, so the ADD_QUEUE from
> amdgpu_userq_map_helper() times out (-110) and an otherwise valid queue
> create fails:
> 
>    amdgpu: MES(0) failed to respond to msg=ADD_QUEUE
>    [drm:mes_userq_map [amdgpu]] *ERROR* Failed to map queue in HW, err (-110)
>    amdgpu: [drm] *ERROR* ... Failed to map Queue
>    amdgpu: [drm] *ERROR* ... Failed to create usermode queue
> 
> Take reset_domain->sem for read around the map so it runs only once MES
> is back up. This mirrors amdgpu_userq_cleanup() and honors the
> userq_mutex -> reset_domain->sem order; the reset path never takes
> userq_mutex, so there is no deadlock.
> 
> Signed-off-by: Jesse Zhang <[email protected]>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> index 652599f08990..770635ab5298 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> @@ -745,7 +745,12 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
>   	if (!adev->userq_halt_for_enforce_isolation ||
>   	    ((queue->queue_type != AMDGPU_HW_IP_GFX) &&
>   	     (queue->queue_type != AMDGPU_HW_IP_COMPUTE))) {
> +		/* Serialize the map against an in-progress GPU reset (MES is
> +		 * unresponsive during recovery), matching amdgpu_userq_cleanup().
> +		 */
> +		down_read(&adev->reset_domain->sem);

If a reset is ongoing and a userq operation comes in the middle, there 
is no need to wait till reset semaphore is available. The ongoing 
process i going to terminate sooner or later after the reset.

This should only try to acquire the lock and return an error if not able to.

Thanks,
Lijo

>   		r = amdgpu_userq_map_helper(queue);
> +		up_read(&adev->reset_domain->sem);
>   		if (r) {
>   			drm_file_err(uq_mgr->file, "Failed to map Queue\n");
>   			trace_amdgpu_userq_create_end(queue, r);