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..
Jason
