[PATCH] drm/ttm: Don't add swapped BOs to swap-LRU list

[Christian König]

Am 18.01.2018 um 06:16 schrieb Felix Kuehling:
> A BO that's already swapped would be added back to the swap-LRU list
> for example if it validation failed under high memory pressure. This
> could later lead to swapping it out again and leaking previous swap
> storage.
>
> This commit adds a condition to prevent that from happening.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 97c3da6..7192473 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -175,7 +175,8 @@ void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
>   		list_add_tail(&bo->lru, &man->lru[bo->priority]);
>   		kref_get(&bo->list_kref);
>   
> -		if (bo->ttm && !(bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
> +		if (bo->ttm && !(bo->ttm->page_flags & TTM_PAGE_FLAG_SG) &&
> +		    !bo->ttm->swap_storage) {

Good catch, but using ttm->swap_storage is the wrong indicator cause on 
some drivers that is always set to something IIRC.

You need to use ttm->page_flags & TTM_PAGE_FLAG_SWAPPED here.

Regards,
Christian.

>   			list_add_tail(&bo->swap,
>   				      &bo->glob->swap_lru[bo->priority]);
>   			kref_get(&bo->list_kref);