Re: [RFC PATCH v2 0/3] expose mapping wrprotect, fix fb_defio use

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Mon, Feb 03, 2025 at 11:24:50AM +0100, Thomas Zimmermann wrote:
> Hi
>
>
> Am 14.01.25 um 00:15 schrieb Lorenzo Stoakes:
> [...]
> >
> > *** REVIEWERS NOTES: ***
> >
> > I do not have any hardware that uses fb_defio, so I'm asking for help with
> > testing this series from those who do :) I have tested the mm side of this,
> > and done a quick compile smoke test of the fb_defio side but this _very
> > much_ requires testing on actual hardware to ensure everything behaves as
> > expected.
>
> With a recent Linux distro, you likely boot up graphics with simpledrm,
> which uses fb_defio as part of its console emulation. To test, boot the
> kernel with the 'nomodeset' parameter and write to /dev/fb0.
>
> Best regards
> Thomas

Thanks, luckily a user kindly tested the series on real hardware and
confirmed it worked, so the series is now un-RFC'd [1] :) but will try this
if it needs significant respin.

[1]:https://lore.kernel.org/all/cover.1738347308.git.lorenzo.stoakes@oracle.com/

>
> >
> > This is based on Andrew's tree [0] in the mm-unstable branch - I was
> > thinking it'd be best to go through the mm tree (with fb_defio maintainer
> > approval, of course!) as it relies upon the mm changes to work correctly.
> >
> > [0]: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/
> >
> > RFC v2:
> > * Updated Jaya Kumar's email on cc - the MAINTAINERS section is apparently incorrect.
> > * Corrected rmap_walk_file() comment to refer to folios as per Matthew.
> > * Reference folio->mapping rather than folio_mapping(folio) in rmap_walk_file()
> >    as per Matthew.
> > * Reference folio->index rather than folio_pgoff(folio) in rmap_walk_file() as
> >    per Matthew.
> > * Renamed rmap_wrprotect_file_page() to mapping_wrprotect_page() as per Matthew.
> > * Fixed kerneldoc and moved to implementation as per Matthew.
> > * Updated mapping_wrprotect_page() to take a struct page pointer as per David.
> > * Removed folio lock when invoking mapping_wrprotect_page() in
> >    fb_deferred_io_work() as per Matthew.
> > * Removed compound_nr() in fb_deferred_io_work() as per Matthew.
> >
> > RFC v1:
> > https://lore.kernel.org/all/1e452b5b65f15a9a5d0c2ed3f5f812fdd1367603.1736352361.git.lorenzo.stoakes@oracle.com/
> >
> > Lorenzo Stoakes (3):
> >    mm: refactor rmap_walk_file() to separate out traversal logic
> >    mm: provide mapping_wrprotect_page() function
> >    fb_defio: do not use deprecated page->mapping, index fields
> >
> >   drivers/video/fbdev/core/fb_defio.c |  38 ++-----
> >   include/linux/fb.h                  |   1 +
> >   include/linux/rmap.h                |   3 +
> >   mm/rmap.c                           | 152 +++++++++++++++++++++++-----
> >   4 files changed, 141 insertions(+), 53 deletions(-)
> >
> > --
> > 2.48.0
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstrasse 146, 90461 Nuernberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
> HRB 36809 (AG Nuernberg)
>