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

[Dmitry Osipenko]

On 1/25/24 13:19, Boris Brezillon wrote:
> On Fri,  5 Jan 2024 21:46:16 +0300
> Dmitry Osipenko <dmitry.osipenko at collabora.com> 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.

We have the signaled-check in the common drm_gem_evict() helper:

https://elixir.bootlin.com/linux/v6.8-rc1/source/drivers/gpu/drm/drm_gem.c#L1496

-- 
Best regards,
Dmitry