diff mbox series

[08/75] mm/gup: Remove an assumption of a contiguous memmap

Message ID 20220204195852.1751729-9-willy@infradead.org (mailing list archive)
State New
Headers show
Series MM folio patches for 5.18 | expand

Commit Message

Matthew Wilcox Feb. 4, 2022, 7:57 p.m. UTC 
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: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
 include/linux/mm.h | 2 ++
 mm/gup.c           | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 213cc569b192..e679a7d66200 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -216,8 +216,10 @@  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 */
diff --git a/mm/gup.c b/mm/gup.c
index 29a8021f10a2..fa75b71820a2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -263,8 +263,8 @@  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;