Re: [PATCH v17 00/12] migrate on fault for device pages

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 12 Nov 2026 19:01:58 +0200 Mika Penttilä <mpenttil@redhat.com> wrote:

> 
> On 11/12/26 18:47, Jason Gunthorpe wrote:
> > On Thu, Nov 12, 2026 at 04:24:05PM +0000, Alexandru Elisei wrote:
> >> Hi Mika,
> >>
> >> On Thu, Nov 12, 2026 at 04:00:09PM +0200, Mika Penttilä wrote:
> >>> Hi Alexandru!
> >>>
> >>> On 11/12/26 13:56, Alexandru Elisei wrote:
> >>>> Hi Mika,
> >>>>
> >>>> I want to help getting this series merged, and I've been familiarizing myself
> >>>> with hmm and device migration, please bare with me if the questions I'm asking
> >>>> are obvious or downright silly.
> >>> Thanks for the interest and willing to help! I am preparing a v18 of the
> >>> series and plan to post it early next week.
> >> The series is big, and as far as I can tell the MM people are hard at work
> >> reviewing bug fixes. It might be better to wait a while, to give people a
> >> chance to have a look? I know that if I see a series being reposted often,
> >> I am less inclined to review the patches since probably a new iteration
> >> will be posted soon. But I can only speak for myself, you know best.
> > It is at v17 and it is still getting high severity sashiko errors
> v14 was first that sashiko managed to review. There was a regression in
> last posting, but also false potsitives, and sashiko reports same issue
> then 3-4 times, so the reality is not that bad. 

Pining for the days when all we had to deal with was checkpatch.  


Mika, afaict the entire patchset is a performance optimization, yet you
say "I don't have a benchmark showing a gain".

Recipients look at patchsets wondering "why should I spend time on
this", especially in these times.  It's best to answer this question
right there in the first sentence of the [0/N].  That means numbers,
and the better they are, the more attention the patchset will get.

>  Documentation/mm/hmm.rst               |   45 +
>  drivers/gpu/drm/nouveau/nouveau_dmem.c |  402 ++++++++-
>  drivers/gpu/drm/nouveau/nouveau_dmem.h |   12 +
>  drivers/gpu/drm/nouveau/nouveau_svm.c  |  155 ++--
>  drivers/gpu/drm/nouveau/nouveau_svm.h  |    5 +
>  include/linux/hmm.h                    |   51 +-
>  include/linux/migrate.h                |   59 +-
>  lib/test_hmm.c                         |  174 +++-
>  lib/test_hmm_uapi.h                    |   21 +-
>  mm/Kconfig                             |    1 +
>  mm/hmm.c                               | 1075 ++++++++++++++++++++++--
>  mm/migrate_device.c                    |  618 +++-----------
>  tools/testing/selftests/mm/hmm-tests.c |   56 ++
>  13 files changed, 1984 insertions(+), 690 deletions(-)

also, yikes!