[PATCH] drm/amdgpu: amdgpu_device_recover_vram got NULL of shadow->parent

[Christian König]

Am 16.04.19 um 09:17 schrieb wentalou:
> amdgpu_bo_destroy had a bug by calling amdgpu_bo_unref outside mutex_lock.
> If amdgpu_device_recover_vram executed between amdgpu_bo_unref and list_del_init,
> it would get NULL of shadow->parent, then caused Call Trace and GPU reset failed.
>
> Change-Id: I41d7b54605e613e87ee03c3ad89c191063c19230
> Signed-off-by: Wentao Lou <Wentao.Lou at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index ec9e450..0df8158 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -88,12 +88,16 @@ static void amdgpu_bo_destroy(struct ttm_buffer_object *tbo)
>   	if (bo->gem_base.import_attach)
>   		drm_prime_gem_destroy(&bo->gem_base, bo->tbo.sg);
>   	drm_gem_object_release(&bo->gem_base);
> -	amdgpu_bo_unref(&bo->parent);
> +	/* in case amdgpu_device_recover_vram got NULL of bo->parent */
>   	if (!list_empty(&bo->shadow_list)) {
>   		mutex_lock(&adev->shadow_list_lock);
>   		list_del_init(&bo->shadow_list);
> +		amdgpu_bo_unref(&bo->parent);
>   		mutex_unlock(&adev->shadow_list_lock);
>   	}
> +	else
> +		amdgpu_bo_unref(&bo->parent);
> +

Please just move amdgpu_bo_unref(&bo->parent); after the "if".

Regards,
Christian.

>   	kfree(bo->metadata);
>   	kfree(bo);
>   }