On Mon, 04 Mar 2024 11:11:28 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> --- a/mm/debug.c~mm-add-__dump_folio-fix-3
> +++ a/mm/debug.c
> @@ -121,23 +121,31 @@ static void __dump_page(const struct pag
> again:
> memcpy(&precise, page, sizeof(*page));
> foliop = page_folio(&precise);
> - idx = folio_page_idx(foliop, page);
> - if (idx != 0) {
> - if (idx < MAX_FOLIO_NR_PAGES) {
> - memcpy(&folio, foliop, 2 * sizeof(struct page));
> - nr_pages = folio_nr_pages(&folio);
> - }
> + if (foliop == (struct folio *)&precise) {
> + idx = 0;
> + if (!folio_test_large(foliop))
> + goto dump;
> + foliop = (struct folio *)page;
> + } else {
> + idx = folio_page_idx(foliop, page);
> + }
> +
> + if (idx < MAX_FOLIO_NR_PAGES) {
> + memcpy(&folio, foliop, 2 * sizeof(struct page));
> + nr_pages = folio_nr_pages(&folio);
> + foliop = &folio;
> + }
>
> - if (idx > nr_pages) {
> - if (loops-- > 0)
> - goto again;
> - printk("page does not match folio\n");
> - precise.compound_head &= ~1UL;
> - foliop = (struct folio *)&precise;
> - idx = 0;
> - }
> + if (idx > nr_pages) {
> + if (loops-- > 0)
> + goto again;
> + printk("page does not match folio\n");
We shouldn't use a bare printk(). I'll make it pr_warn(), but should
we be using WARN() here to get a backtrace?
> + precise.compound_head &= ~1UL;
> + foliop = (struct folio *)&precise;
> + idx = 0;
> }
