On Fri, Feb 05, 2021 at 08:41:26PM +0000, Joao Martins wrote:

Add a unpin_user_page_range_dirty_lock() API which takes a starting page
and how many consecutive pages we want to unpin and optionally dirty.

To that end, define another iterator for_each_compound_range()
that operates in page ranges as opposed to page array.

For users (like RDMA mr_dereg) where each sg represents a
contiguous set of pages, we're able to more efficiently unpin
pages without having to supply an array of pages much of what
happens today with unpin_user_pages().

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joao Martins <redacted>
---
 include/linux/mm.h |  2 ++
 mm/gup.c           | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

+/**
+ * unpin_user_page_range_dirty_lock() - release and optionally dirty
+ * gup-pinned page range
+ *
+ * @page:  the starting page of a range maybe marked dirty, and definitely released.
+ * @npages: number of consecutive pages to release.
+ * @make_dirty: whether to mark the pages dirty
+ *
+ * "gup-pinned page range" refers to a range of pages that has had one of the
+ * get_user_pages() variants called on that page.

Tidy this language though, this only works with the pin_user_pages
variants because it hardwires FOLL_PIN

Jason