Re: [syzbot] [mm?] kernel BUG in collapse_scan_file

[Lorenzo Stoakes (Oracle)]

On Thu, Mar 19, 2026 at 12:10:36PM +0100, David Hildenbrand (Arm) wrote:
> >> "This isn't the kind of thing where you can just jump in with a one line
> >> patch and actually be helpful, sorry."
> >
> >
> > Yup, so again really I don't think the kernel should take the xarray debug patch
> > until it is discussed and verified as correct on-list.
> >
> > See the discussion with Vlastimil.
>
> Agreed.
>
> >
> >>
> >> So I am clueless if there is a real problem there or whether it's just a
> >> false positive. And whether (if it's a real problem) the simple fix
> >> would actually be a good temporary fix ("make other bugs more likely").
> >>
> >> I can try finding some time to look into that, but pagecache code is not
> >> particularly the code I'm familiar with ...
> >
> > I don't think we should waste our time on it, willy's series should be yoinked
> > until it can prove itself for-sure well behaved.
>
> I hear you. At the same time it has the smell of "test case fails, so
> let's remove the test case" vibes.
>
> Well, arguable, it's worse than a test case that fails :(
>
> I'm fine with dropping that asap. At the same time, I hope we won't lose
> our reminder that something possibly bad is broken upstream.

I mean hopefully once we have a _working_ version of this it will get reflagged
again in any case.

The uncertainty makes this worse than a bug report unfortunately because it's a
maybe/maybe not and there's literally nothing we can do with that :(

>
> --
> Cheers,
>
> David

Thanks, Lorenzo