Commit 4c654229 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/gup: Remove an assumption of a contiguous memmap 



This assumption needs the inverse of nth_page(), which is temporarily
named page_nth() until it's renamed later in this series.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
parent c228afb1

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -212,8 +212,10 @@ int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *, 


#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)

#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))

#define page_nth(head, tail)	(page_to_pfn(tail) - page_to_pfn(head))

#else

#define nth_page(page,n) ((page) + (n))

#define page_nth(head, tail)	((tail) - (head))

#endif



/* to align the pointer to the (next) page boundary */

mm/gup.c

+2 −2
Original line number Diff line number Diff line
@@ -261,8 +261,8 @@ static inline struct page *compound_range_next(struct page *start, 
	next = nth_page(start, i);

	page = compound_head(next);

	if (PageHead(page))

		nr = min_t(unsigned int,

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

		nr = min_t(unsigned int, npages - i,

			   compound_nr(page) - page_nth(page, next));



	*ntails = nr;

	return page;