This assumption needs the inverse of nth_page(), which I've temporarily named page_nth() until someone comes up with a better name. Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> --- include/linux/mm.h | 2 ++ mm/gup.c | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index d8b7d7ed14dd..f2f3400665a4 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 9c0a702a4e03..afb638a30e44 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -238,8 +238,8 @@ static inline struct page *compound_range_next(unsigned long i, 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; -- 2.33.0
