Re: [PATCH v19 22/30] drm/shmem-helper: Add common memory shrinker

[Boris Brezillon <boris.brezillon@collabora.com>]

On Fri,  5 Jan 2024 21:46:16 +0300
Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:

> +/**
> + * drm_gem_shmem_swapin_locked() - Moves shmem GEM back to memory and enables
> + *                                 hardware access to the memory.
> + * @shmem: shmem GEM object
> + *
> + * This function moves shmem GEM back to memory if it was previously evicted
> + * by the memory shrinker. The GEM is ready to use on success.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +int drm_gem_shmem_swapin_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	int err;
> +
> +	dma_resv_assert_held(shmem->base.resv);
> +
> +	if (!shmem->evicted)
> +		return 0;

Shouldn't we have a drm_gem_shmem_shrinker_update_lru_locked() even if
the object wasn't evicted, such that idle->busy transition moves the BO
to the list tail?

> +
> +	err = drm_gem_shmem_acquire_pages(shmem);
> +	if (err)
> +		return err;
> +
> +	shmem->evicted = false;
> +
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_swapin_locked);
> +