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

[Lorenzo Stoakes (Oracle)]

On Thu, Mar 19, 2026 at 10:21:40AM +0100, David Hildenbrand (Arm) wrote:
> On 3/19/26 10:14, Lance Yang wrote:
> >
> >
> > On 2026/3/19 17:00, David Hildenbrand (Arm) wrote:
> >> On 3/19/26 09:53, Lorenzo Stoakes (Oracle) wrote:
> >>>
> >>> Hmm we shouldn't leave this bug in place while working for a fancier
> >>> fix??
> >>>
> >>> Can we get _something_ going as an upstream fix? We can improve
> >>> whatever we do
> >>> later right?
> >>>
> >>> David, thoughts?
> >>
> >> I recall Willy mentioning that the issue is likely a false positive.
> >>
> >> IIUC, that commit is not upstream? So it only triggers in linux-next.
> >
> > Right. That does not appear to be in upstream, I only see it in linux-
> > next :)
> >
> >> Which means:
> >>
> >> 1) If it's a false positive, upstream is not effected (no XA_NODE_BUG_ON)
> >>
> >> 2) If it's not a false positive, upstream is effected but does not
> >> trigger the XA_NODE_BUG_ON
> >
> > Yep. So this particular BUG_ON is not affecting upstream directly.
> >
> > That said, syzbot will likely keep hitting it in linux-next and
> > generating noise for us until it is addressed there ...
>
> Right, I assume this comes through Willy's tree, so Willy should
> consider removing it for the time being.
>
> --
> Cheers,
>
> David

OK guys you had your fun, yes I misspoke by saying upstream, I apologise. No
need to go over that repeatedly.

However, linux-next ends up in upstream unless action is taken to fix patches
heading there.

We shouldn't, really, be just ignoring splatting kernels like that. At least
that's my personal point of view on it.

But anyway I really don't have the time or energy to try to track this down or
push on this further.

Thanks, Lorenzo