On Fri, Nov 10, 2023 at 11:33:22AM +0800, Kefeng Wang wrote: > Replace seven implicit calls to compound_head() with one page_folio(). You're so focused on trying to accomplish your goal (killing off the page_idle and page_young functions) that you're doing a poor job thinkig about the conversions you're doing along the way. > +++ b/fs/proc/task_mmu.c > @@ -445,23 +445,25 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page, > { > int i, nr = compound ? compound_nr(page) : 1; > unsigned long size = nr * PAGE_SIZE; > + struct folio *folio = page_folio(page); Stop right here. The use of compound_nr() should give you pause. After looking at how smaps_account() is used, it seems to me that the two callers should each pass in PAGE_SIZE or PMD_SIZE instead of doing this calculation. More generally, step back from this series. Do a good job of transforming fs/proc/task_mmu.c to use folios. Once you've done that, you can approach the young/idle work again.