fixing sashiko failure to apply (was Re: [PATCH v5 00/16] mm/rmap: index MAP_PRIVATE file-backed folios by anonymous pgoff)

[ trim cc list ]

+cc Roman

On Fri, Aug 14, 2026 at 02:13:51AM -0700, Matthew Brost wrote:
> On Fri, Aug 14, 2026 at 10:01:19AM +0100, Lorenzo Stoakes (ARM) wrote:
> > On Thu, Aug 13, 2026 at 11:53:46AM -0700, Andrew Morton wrote:
> > > You'll be mortified to hear that Sashiko wasn't able to find anything
> > > to which to apply this.
> >
> > :))
> >
> > Well, when it's right it's useful, when it's wrong or suggesting unrelated
> > what-nots it's less useful :>)
> >
>
> Questioning your assumptions is useful, even when they turn out to be wrong.
> Show more lines
>
> > I do locally put things through claude + Chris Mason's prompts a lot, I
> > don't always invoke local sashiko as it's very slow and token-heavy or has
> > been so far, but am planning to do that more also in future.
> >
>
> Yes, it's kind of odd that Sashiko burns more tokens than a full day of
> breakfast, lunch, and dinner service. Running Sashiko is a bottleneck in
> my workflow, so I'll defer to others on this list.

Yup, not sure if there are recommended configs for something saner :)

Maybe Roman has some advice on that?

>
> > >
> > > Sashiko can be guided with a base-commit: tag but I'm not sure how to
> > > tell it what tree/branch to try, or even if that's necessary.  Perhaps
> > > someone can figure this out sometime.
> >
> > b4 gives a base commit, but I think because the trees are rebased it ends
> > up being the incorrect one.
> >
> > Not sure what the solution is!
> >
>
> We have seen this on the Xe list (our list is based on drm-tip),
> typically with cross-subsystem patches. Some cross-subsystem patches
> apply and run correctly, while others do not but public CI flows run
> based on drm-tip. I do not have a bisect or a clear understanding of
> what works and what doesn't, but I think it would be very useful if the
> community could better understand the root cause.

As Mike said, mm-unstable/mm-new is heavily rebased and also carries the old
version of the series before the new one is applied, so it's super unclear what
the base commit should be there.

But in general, I wonder if it's possible that we could tell sashiko
after-the-fact what base commit to look at once the series is in, or re-trigger
it somehow once it's in-tree?

Roman - any suggestions on what we could do to help sashiko find things?

(Once mm-next is in place everything with change again, but can address that
then :)

>
> Matt
>

--
Cheers, Lorenzo