Re: [RFC][PATCH v6 3/7] drm: ttm_pool: Rework ttm_pool_free_page to allow us to use it as a function pointer

[Christian König]

Am 05.02.21 um 20:47 schrieb John Stultz:
> On Fri, Feb 5, 2021 at 12:28 AM Christian König
> <christian.koenig@xxxxxxx> wrote:
> > Am 05.02.21 um 09:06 schrieb John Stultz:
> > > This refactors ttm_pool_free_page(), and by adding extra entries
> > > to ttm_pool_page_dat, we then use it for all allocations, which
> > > allows us to simplify the arguments needed to be passed to
> > > ttm_pool_free_page().
> > This is a clear NAK since the peer page data is just a workaround for
> > the DMA-API hack to grab pages from there.
> >
> > Adding this to all pages would increase the memory footprint drastically.
> Yea, that's a good point!  Hrm... bummer. I'll have to see if there's
> some other way I can get the needed context for the free from the
> generic page-pool side.

What exactly is the problem here? As far as I can see we just have the 
lru entry (list_head) and the pool.

How the lru is cast to the page can be completely pool implementation 
specific.

Regards,
Christian.

> Thanks so much for the review!
> -john