Commit 458a4f78 authored by Joao Martins's avatar Joao Martins Committed by Linus Torvalds
Browse files

mm/gup: add a range variant of unpin_user_pages_dirty_lock() 

Add an 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().

Link: https://lkml.kernel.org/r/20210212130843.13865-4-joao.m.martins@oracle.com


Suggested-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarJoao Martins <joao.m.martins@oracle.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 31b912de

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -1265,6 +1265,8 @@ static inline void put_page(struct page *page) 
void unpin_user_page(struct page *page);

void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,

				 bool make_dirty);

void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,

				      bool make_dirty);

void unpin_user_pages(struct page **pages, unsigned long npages);



/**

mm/gup.c

+62 −0
Original line number Diff line number Diff line
@@ -213,6 +213,32 @@ void unpin_user_page(struct page *page) 
}

EXPORT_SYMBOL(unpin_user_page);



static inline void compound_range_next(unsigned long i, unsigned long npages,

				       struct page **list, struct page **head,

				       unsigned int *ntails)

{

	struct page *next, *page;

	unsigned int nr = 1;



	if (i >= npages)

		return;



	next = *list + i;

	page = compound_head(next);

	if (PageCompound(page) && compound_order(page) >= 1)

		nr = min_t(unsigned int,

			   page + compound_nr(page) - next, npages - i);



	*head = page;

	*ntails = nr;

}



#define for_each_compound_range(__i, __list, __npages, __head, __ntails) \

	for (__i = 0, \

	     compound_range_next(__i, __npages, __list, &(__head), &(__ntails)); \

	     __i < __npages; __i += __ntails, \

	     compound_range_next(__i, __npages, __list, &(__head), &(__ntails)))



static inline void compound_next(unsigned long i, unsigned long npages,

				 struct page **list, struct page **head,

				 unsigned int *ntails)
@@ -301,6 +327,42 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages, 
}

EXPORT_SYMBOL(unpin_user_pages_dirty_lock);



/**

 * 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

 * pin_user_pages() variants called on that page.

 *

 * For the page ranges defined by [page .. page+npages], make that range (or

 * its head pages, if a compound page) dirty, if @make_dirty is true, and if the

 * page range was previously listed as clean.

 *

 * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is

 * required, then the caller should a) verify that this is really correct,

 * because _lock() is usually required, and b) hand code it:

 * set_page_dirty_lock(), unpin_user_page().

 *

 */

void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,

				      bool make_dirty)

{

	unsigned long index;

	struct page *head;

	unsigned int ntails;



	for_each_compound_range(index, &page, npages, head, ntails) {

		if (make_dirty && !PageDirty(head))

			set_page_dirty_lock(head);

		put_compound_head(head, ntails, FOLL_PIN);

	}

}

EXPORT_SYMBOL(unpin_user_page_range_dirty_lock);



/**

 * unpin_user_pages() - release an array of gup-pinned pages.

 * @pages:  array of pages to be marked dirty and released.