[PATCH 1/1] drm/ttm: return -EBUSY if waiting for busy BO fails

Koenig, Christian Christian.Koenig at amd.com
Wed Jun 26 06:54:48 UTC 2019


Am 26.06.19 um 08:40 schrieb Kuehling, Felix:
> Returning -EAGAIN prevents ttm_bo_mem_space from trying alternate
> placements and can lead to live-locks in amdgpu_cs, retrying
> indefinitely and never succeeding.
>
> Fixes: cfcc52e477e4 ("drm/ttm: fix busy memory to fail other user v10")
> CC: Christian Koenig <Christian.Koenig at amd.com>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>

Crap, I feared that this could live-lock under some circumstances, but 
hoped that this would be a rather rare case.

How did you reproduce this?

Anyway patch is Reviewed-by: Christian K├Ânig <christian.koenig at amd.com> 
for now.

> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index c7de667d482a..58c403eda04e 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -827,7 +827,7 @@ static int ttm_mem_evict_wait_busy(struct ttm_buffer_object *busy_bo,
>   	if (!r)
>   		reservation_object_unlock(busy_bo->resv);
>   
> -	return r == -EDEADLK ? -EAGAIN : r;
> +	return r == -EDEADLK ? -EBUSY : r;
>   }
>   
>   static int ttm_mem_evict_first(struct ttm_bo_device *bdev,



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