Re: [PATCH v4 2/3] mm: introduce put_user_page*(), placeholder versions

From: Andrew Morton
Date: Wed Oct 10 2018 - 19:44:05 EST

On Tue, 9 Oct 2018 17:32:16 -0700 John Hubbard <jhubbard@xxxxxxxxxx> wrote:

> > I'm not really understanding. Patch 3/3 changes just one infiniband
> > driver to use put_user_page(). But the changelogs here imply (to me)
> > that every user of get_user_pages() needs to be converted to
> > s/put_page/put_user_page/.
> >
> > Methinks a bit more explanation is needed in these changelogs?
> >
> OK, yes, it does sound like the explanation is falling short. I'll work on something
> clearer. Did the proposed steps in the changelogs, such as:
> [2]
> Proposed steps for fixing get_user_pages() + DMA problems.
> help at all, or is it just too many references, and I should write the words
> directly in the changelog?
> Anyway, patch 3/3 is a just a working example (which we do want to submit, though), and
> many more conversions will follow. But they don't have to be done all upfront--they
> can be done in follow up patchsets.
> The put_user_page*() routines are, at this point, not going to significantly change
> behavior.
> I'm working on an RFC that will show what the long-term fix to get_user_pages and
> put_user_pages will look like. But meanwhile it's good to get started on converting
> all of the call sites.

I see. Yes, please do put all of it into the changelog[s].