Re: [PATCH 2/2] drm/i915: Unpin stolen pages

[Ben Widawsky <ben@bwidawsk.net>]

On Mon, Jun 03, 2013 at 10:52:12AM +0200, Daniel Vetter wrote:
> On Mon, Jun 03, 2013 at 09:36:48AM +0100, Chris Wilson wrote:
> > On Sat, Jun 01, 2013 at 03:13:04PM +0200, Daniel Vetter wrote:
> > > On Sat, Jun 1, 2013 at 1:34 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > > > On Sat, Jun 01, 2013 at 11:17:10AM +0200, Daniel Vetter wrote:
> > > >> On Sat, Jun 1, 2013 at 1:51 AM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > > >> > That neatly explains the WARN. Not too happy about accumulating lots of
> > > >> > backing storage specific processing into free_object, but that can be
> > > >> > fixed up later (there is an obj->ops->release() pending).
> > > >>
> > > >> I'm more irked with the semantic overloading of object pinning. Might
> > > >> be cleaner to otherwise mark stolen obejcts as not shrinkable instead
> > > >> of pinning them for their entire lifetime. But we can bikeshed that
> > > >> later on ;-)
> > > >
> > > > Some merit to that argument, but it still feels correct to say that the
> > > > stolen pages are pinned for their lifetime. Given obj->ops->release(),
> > > > it does actually become simpler to not mess around with pin_count. So
> > > > later it is.
> > > 
> > > I was more unhappy that pin_count has different meanings, until I've
> > > noticed that we've fixed that up already with the introduction of
> > > ->pages_pin_count. Shouldn't stolen mem just hold a reference on that
> > > one? After all unbinding from the gtt is ok with stolen memory, but
> > > dropping the backing storage in the shrinker won't work. Not that we
> > > currently use stolen for anything else than permanently pinned bos.
> > 
> > As mentioned on irc, stolen does use the pages_pin_count for its
> > purposes. The purpose of this patch is purely to allow sanity checking
> > the pages_pin_count with a WARN_ON during free which seems sensible but
> > not strictly required.
> 
> Yeah, silly me didn't read the code before sending a knee-jerk mail ;-)
> 
> Series merged (hopefully in the right order and all, please check), thanks
> for the patches and review.
> -Daniel
>
>
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

Order looks good. Thanks.

-- 
Ben Widawsky, Intel Open Source Technology Center