From: Joao Martins <joao.m.martins@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Doug Ledford <dledford@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 2 + mm/gup.c | 62 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 64 insertions(+) --- a/include/linux/mm.h~mm-gup-add-a-range-variant-of-unpin_user_pages_dirty_lock +++ a/include/linux/mm.h @@ -1265,6 +1265,8 @@ static inline void put_page(struct 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); /** --- a/mm/gup.c~mm-gup-add-a-range-variant-of-unpin_user_pages_dirty_lock +++ a/mm/gup.c @@ -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) @@ -302,6 +328,42 @@ void unpin_user_pages_dirty_lock(struct 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. * @npages: number of pages in the @pages array. _
