Re: [PATCH v3 13/28] drm/amdgpu: add missing lock when using ttm entities

["Christian König" <christian.koenig@amd.com>]

On 11/21/25 11:12, Pierre-Eric Pelloux-Prayer wrote:
> Taking the entity lock is required to guarantee the ordering of
> execution. The next commit will add a check that the lock is
> held.
> 
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>

The benchmarking is kind of irrelevant, but adding the other lock should actually be the first patch in the series since it is a bug fix (it needs to grab the gart window lock at this place of course).

Then the patch needs a CC stable and a Fixes tag to the patch who introduced amdgpu_ttm_access_memory_sdma().

With that done: Reviewed-by: Christian König <christian.koenig@amd.com>

Regards,
Christian.

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c | 2 ++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c
> index a050167e76a4..832d9ae101f0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_benchmark.c
> @@ -35,6 +35,7 @@ static int amdgpu_benchmark_do_move(struct amdgpu_device *adev, unsigned size,
>  	struct dma_fence *fence;
>  	int i, r;
>  
> +	mutex_lock(&adev->mman.default_entity.lock);
>  	stime = ktime_get();
>  	for (i = 0; i < n; i++) {
>  		r = amdgpu_copy_buffer(adev, &adev->mman.default_entity,
> @@ -47,6 +48,7 @@ static int amdgpu_benchmark_do_move(struct amdgpu_device *adev, unsigned size,
>  		if (r)
>  			goto exit_do_move;
>  	}
> +	mutex_unlock(&adev->mman.default_entity.lock);
>  
>  exit_do_move:
>  	etime = ktime_get();
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 3a0511d1739f..a803af015d05 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1501,6 +1501,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
>  	if (r)
>  		goto out;
>  
> +	mutex_lock(&adev->mman.default_entity.lock);
>  	amdgpu_res_first(abo->tbo.resource, offset, len, &src_mm);
>  	src_addr = amdgpu_ttm_domain_start(adev, bo->resource->mem_type) +
>  		src_mm.start;
> @@ -1512,6 +1513,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
>  				PAGE_SIZE, 0);
>  
>  	fence = amdgpu_ttm_job_submit(adev, job, num_dw);
> +	mutex_unlock(&adev->mman.default_entity.lock);
>  
>  	if (!dma_fence_wait_timeout(fence, false, adev->sdma_timeout))
>  		r = -ETIMEDOUT;