On Fri, Mar 07, 2025 at 12:39:55PM -0500, Zi Yan wrote:
> + for (index = new_nr_pages; index < nr_pages; index += new_nr_pages) {
> + struct page *head = &folio->page;
> + struct page *new_head = head + index;
> +
> + /*
> + * Careful: new_folio is not a "real" folio before we cleared PageTail.
> + * Don't pass it around before clear_compound_head().
> + */
> + struct folio *new_folio = (struct folio *)new_head;
[...]
> + /* ->mapping in first and second tail page is replaced by other uses */
> + VM_BUG_ON_PAGE(new_nr_pages > 2 && new_head->mapping != TAIL_MAPPING,
> + new_head);
> + new_head->mapping = head->mapping;
> + new_head->index = head->index + index;
Why are you using new_head->mapping and ->index instead of new_folio?
