Re: [PATCH v3 00/23] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM

[John Hubbard]

On 11/13/19 3:43 AM, Daniel Vetter wrote:
...
> > > > Can't we call this unpin_user_page then, for some symmetry? Or is that
> > > > even more churn?
> > > >
> > > > Looking from afar the naming here seems really confusing.
> > >
> > >
> > > That look from afar is valuable, because I'm too close to the problem to see
> > > how the naming looks. :)
> > >
> > > unpin_user_page() sounds symmetrical. It's true that it would cause more
> > > churn (which is why I started off with a proposal that avoids changing the
> > > names of put_user_page*() APIs). But OTOH, the amount of churn is proportional
> > > to the change in direction here, and it's really only 10 or 20 lines changed,
> > > in the end.
> > >
> > > So I'm open to changing to that naming. It would be nice to hear what others
> > > prefer, too...
> >
> > FWIW I'd find unpin_user_page() also better than put_user_page() as a
> > counterpart to pin_user_pages().
>
> One more point from afar on pin/unpin: We use that a lot in graphics for
> permanently pinned graphics buffer objects. Which really only should be
> used for scanout. So at least graphics folks should have an appropriate
> mindset and try to make sure we don't overuse this stuff.
> -Daniel

OK, Ira also likes "unpin", and so far no one has said *anything* in favor
of the "put_user_page" names, so I think we have a winner! I'll change the
names to unpin_user_page*().


thanks,
--
John Hubbard
NVIDIA