[PATCH] drm/ttm: fix pipelined gutting for evictions

[Felix Kuehling]

Am 2020-07-23 um 5:00 a.m. schrieb Christian König:
> We can't pipeline that during eviction because the memory needs
> to be available immediately.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index bc2230ecb7e3..122040056a07 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -651,8 +651,16 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
>  	placement.num_busy_placement = 0;
>  	bdev->driver->evict_flags(bo, &placement);
>  
> -	if (!placement.num_placement && !placement.num_busy_placement)
> -		return ttm_bo_pipeline_gutting(bo);
> +	if (!placement.num_placement && !placement.num_busy_placement) {
> +		ttm_bo_wait(bo, false, false);
> +
> +		ttm_tt_destroy(bo->ttm);
> +
> +		memset(&bo->mem, 0, sizeof(bo->mem));

Where does the memory in the bo->mem (ttm_mem_reg) get destroyed? It
doesn't get attached to a ghost BO in this case, so someone will have to
call ttm_bo_mem_put explicitly before you wipe out bo->mem.

Regards,
  Felix


> +		bo->mem.mem_type = TTM_PL_SYSTEM;
> +		bo->ttm = NULL;
> +		return 0;
> +	}
>  
>  	evict_mem = bo->mem;
>  	evict_mem.mm_node = NULL;