On Fri, May 14, 2021 at 05:55:46PM +0200, Vlastimil Babka wrote: > On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote: > > folio_index() is the equivalent of page_index() for folios. > > folio_file_page() is the equivalent of find_subpage(). > > find_subpage() special cases hugetlbfs, folio_file_page() doesn't. > > > folio_contains() is the equivalent of thp_contains(). > > Yet here, both thp_contains() and folio_contains() does. > > This patch doesn't add users so maybe it becomes obvious later, but perhaps > worth explaining in the changelog or comment? No, you're right, this is a bug. I originally had it in my mind that hugetlbfs wouldn't need to do this any more because it can just use the folio interfaces and never try to find the subpage. But I don't understand all the cases well enough to be sure that they're all gone, and they certainly don't all go as part of this patch series. So I think I need to reintroduce the check-for-hugetlb to folio_file_page() and we can look at removing it later once we're sure that nobody is using the interfaces that return pages from the page cache any more. Or we convert hugetlbfs to use the page cache the same way as every other filesystem ;-) Thanks for spotting that.
