On Thu, 2019-04-04 at 16:45 +0300, Kirill A. Shutemov wrote:
> What about this:
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index f939e004c5d1..2e8438a1216a 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -335,12 +335,15 @@ static inline struct page *grab_cache_page_nowait(struct
> address_space *mapping,
>
> static inline struct page *find_subpage(struct page *page, pgoff_t offset)
> {
> - unsigned long index = page_index(page);
> + unsigned long mask;
> +
> + if (PageHuge(page))
> + return page;
>
> VM_BUG_ON_PAGE(PageTail(page), page);
> - VM_BUG_ON_PAGE(index > offset, page);
> - VM_BUG_ON_PAGE(index + (1 << compound_order(page)) <= offset, page);
> - return page - index + offset;
> +
> + mask = (1UL << compound_order(page)) - 1;
> + return page + (offset & mask);
> }
>
> struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
It works fine.
