On Thu, Apr 04, 2024 at 10:17:26AM -0700, Lokesh Gidra wrote:
> - folio_move_anon_rmap(src_folio, dst_vma);
> - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr));
> -
> src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd);
> /* Folio got pinned from under us. Put it back and fail the move. */
> if (folio_maybe_dma_pinned(src_folio)) {
> @@ -2270,6 +2267,9 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
> goto unlock_ptls;
> }
>
> + folio_move_anon_rmap(src_folio, dst_vma);
> + WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr));
> +
This use of WRITE_ONCE scares me. We hold the folio locked. Why do
we need to use WRITE_ONCE? Who's looking at folio->index without
holding the folio lock?
