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

[Boris Brezillon]

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

> +static bool drm_gem_shmem_is_evictable(struct drm_gem_shmem_object *shmem)
> +{
> +	return (shmem->madv >= 0) && shmem->base.funcs->evict &&
> +		refcount_read(&shmem->pages_use_count) &&
> +		!refcount_read(&shmem->pages_pin_count) &&
> +		!shmem->base.dma_buf && !shmem->base.import_attach &&
> +		!shmem->evicted;

Are we missing

                && dma_resv_test_signaled(shmem->base.resv,
					  DMA_RESV_USAGE_BOOKKEEP)

to make sure the GPU is done using the BO?
The same applies to drm_gem_shmem_is_purgeable() BTW.

If you don't want to do this test here, we need a way to let drivers
provide a custom is_{evictable,purgeable}() test.

I guess we should also expose drm_gem_shmem_shrinker_update_lru_locked()
to let drivers move the GEMs that were used most recently (those
referenced by a GPU job) at the end of the evictable LRU.

> +}
> +