Re: [PATCH 2/2] drm/ttm: Move pinned objects off LRU lists when pinning

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

Am 02.09.24 um 17:41 schrieb Thomas Hellström:
> The ttm_bo_pin() and ttm_bo_unpin() functions weren't moving their
> resources off the LRU list to the unevictable list.
>
> Make sure that happens so that pinned objects don't accidently linger
> on the LRU lists, and also make sure to move them back once they
> are unpinned.
>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: <dri-devel@lists.freedesktop.org>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

I really can't figure out why we removed that. Anyway Reviewed-by: 
Christian König <christian.koenig@amd.com> for now.

> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index d244566a7e48..057a65f51969 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -592,9 +592,10 @@ void ttm_bo_pin(struct ttm_buffer_object *bo)
>   	dma_resv_assert_held(bo->base.resv);
>   	WARN_ON_ONCE(!kref_read(&bo->kref));
>   	spin_lock(&bo->bdev->lru_lock);
> -	if (bo->resource)
> +	if (!bo->pin_count++ && bo->resource) {
>   		ttm_resource_del_bulk_move(bo->resource, bo);
> -	++bo->pin_count;
> +		ttm_resource_move_to_lru_tail(bo->resource);
> +	}
>   	spin_unlock(&bo->bdev->lru_lock);
>   }
>   EXPORT_SYMBOL(ttm_bo_pin);
> @@ -613,9 +614,10 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo)
>   		return;
>   
>   	spin_lock(&bo->bdev->lru_lock);
> -	--bo->pin_count;
> -	if (bo->resource)
> +	if (!--bo->pin_count && bo->resource) {
>   		ttm_resource_add_bulk_move(bo->resource, bo);
> +		ttm_resource_move_to_lru_tail(bo->resource);
> +	}
>   	spin_unlock(&bo->bdev->lru_lock);
>   }
>   EXPORT_SYMBOL(ttm_bo_unpin);