On Mon 09-07-18 09:53:57, Jason Gunthorpe wrote:
> On Mon, Jul 09, 2018 at 01:05:53AM -0700, john.hubbard@xxxxxxxxx wrote:
> > From: John Hubbard <jhubbard@xxxxxxxxxx>
> >
> > Introduces put_user_page(), which simply calls put_page().
> > This provides a safe way to update all get_user_pages*() callers,
> > so that they call put_user_page(), instead of put_page().
> >
> > Also adds release_user_pages(), a drop-in replacement for
> > release_pages(). This is intended to be easily grep-able,
> > for later performance improvements, since release_user_pages
> > is not batched like release_pages is, and is significantly
> > slower.
> >
> > Subsequent patches will add functionality to put_user_page().
> >
> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> > include/linux/mm.h | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index a0fbb9ffe380..db4a211aad79 100644
> > +++ b/include/linux/mm.h
> > @@ -923,6 +923,20 @@ static inline void put_page(struct page *page)
> > __put_page(page);
> > }
> >
> > +/* Placeholder version, until all get_user_pages*() callers are updated. */
> > +static inline void put_user_page(struct page *page)
> > +{
> > + put_page(page);
> > +}
> > +
> > +/* A drop-in replacement for release_pages(): */
> > +static inline void release_user_pages(struct page **pages,
> > + unsigned long npages)
> > +{
> > + while (npages)
> > + put_user_page(pages[--npages]);
> > +}
> > +
> > #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
> > #define SECTION_IN_PAGE_FLAGS
> > #endif
>
> Just as question: Do you think it is worthwhile to have a
> release_user_page_dirtied() helper as well?
>
> Ie to indicate that a pages that were grabbed under GUP FOLL_WRITE
> were actually written too?
>
> Keeps more of these unimportant details out of the drivers..
Yeah, I think that would be nice as well.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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