On Tue, Aug 15, 2023 at 04:26:44AM +0100, Matthew Wilcox (Oracle) wrote:
> Move PG_writeback into bottom byte so that it can use PG_waiters in a
> later patch. Move PG_head into bottom byte as well to match with where
> 'order' is moving next. PG_active and PG_workingset move into the second
> byte to make room for them.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> include/linux/page-flags.h | 24 +++++++++++-------------
> 1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index aabf50dc71a3..6a0dd94b2460 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -99,13 +99,15 @@
> */
> enum pageflags {
> PG_locked, /* Page is locked. Don't touch. */
> + PG_writeback, /* Page is under writeback */
> PG_referenced,
> PG_uptodate,
> PG_dirty,
> PG_lru,
> + PG_head, /* Must be in bit 6 */
Could there be some explanation on "must be in bit 6" here?
Thanks,
--
Peter Xu
