[Intel-gfx] [PATCH] drm/i915: Allow shrinking of userptr objects once again

[Chris Wilson]

On Tue, Nov 01, 2016 at 01:28:06PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Commit 1bec9b0bda3d ("drm/i915/shrinker: Only shmemfs objects
> are backed by swap") stopped considering the userptr objects
> in shrinker callbacks.
> 
> Restore that so idle userptr objects can be discarded in order
> to free up memory.
> 
> One change further to what was introduced in 1bec9b0bda3d is
> to start considering userptr objects in oom but that should
> also be a correct thing to do.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Fixes: 1bec9b0bda3d ("drm/i915/shrinker: Only shmemfs objects are backed by swap")
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> Cc: <stable at vger.kernel.org>
> ---
>  drivers/gpu/drm/i915/i915_gem_shrinker.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> index 0993afc0e725..dfca1f6b3630 100644
> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> @@ -83,8 +83,8 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
>  	if (!obj->mm.pages)
>  		return false;
>  
> -	/* Only shmemfs objects are backed by swap */
> -	if (!obj->base.filp)
> +	/* shmemfs and userptr objects are backed by swap */
> +	if (!obj->base.filp && !obj->userptr.mm)

Hmm. Another sticking point if we want to use the union again.

How about obj->ops->flags & I915_GEM_OBJECT_HAS_BACKING_STORE ?
Or I915_GEM_OBJECT_CAN_SWAP since we want this for i915_gem_internal.c
as well, and that techinically doesn't have a backing store but can be
reaped. Hmm.

if (!(obj->ops->flags & I915_GEM_OBJECT_HAS_BACKING_STORE ||
      obj->mm.madv == I915_MADV_DONTNEED))

-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre