Let's cc Joao. On Tue, 7 Jun 2022 22:41:57 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote: > compound_pincount_ptr is stored at first tail page instead of second tail > page now. "now"? Some identifiable commit did this? > And if it or some other field changes again in the future, data > overwritten might happen. Calling prep_compound_head() outside the loop > to prevent such possible issue. No functional change intended. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6772,17 +6772,8 @@ static void __ref memmap_init_compound(struct page *head, > __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); > prep_compound_tail(head, pfn - head_pfn); > set_page_count(page, 0); > - > - /* > - * The first tail page stores compound_mapcount_ptr() and > - * compound_order() and the second tail page stores > - * compound_pincount_ptr(). Call prep_compound_head() after > - * the first and second tail pages have been initialized to > - * not have the data overwritten. > - */ > - if (pfn == head_pfn + 2) > - prep_compound_head(head, order); > } > + prep_compound_head(head, order); > } > > void __ref memmap_init_zone_device(struct zone *zone,
