Re: [RFC PATCH 3/6] mm: nommu: fix an issue on map request to /dev/zero

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Aug 13, 2026 at 10:51:39PM +0900, Daniel Palmer wrote:
> HI Lorenzo,
> 
> On Thu, 13 Aug 2026 at 22:30, Lorenzo Stoakes (ARM) <ljs@kernel.org> wrote:
> > > One of the big problems for nommu seems to be that everyone is
> > > convinced it is completely unused and totally broken. :)
> >
> > No, the issue is that nobody seems to do any testing or contribute any code
> > aside from at least Hajime (thanks Haijme :), and possibly others (forgive me if
> > I am missing people's names here!)
> 
> > There's been situtions where nommu has been broken for a year and _nobody
> > noticed_.
> >
> > And yet whenever nommu comes up people always seem to pop up and say how
> > important it is, then mention a talk etc.
> 
> It also broke sometime around LPC 2025, I spotted it, reported it..
> and told the people in the room at LPC for the nommu talk that it was
> borken and maybe they should take a look. :)
> I think I maybe even told Tazaki-san in person that it was currently
> broken in the hall outside of the session.
> 
> > Well if it's important, test it. Test the tip kernel. Report bugs. Contribute
> > code. Any or all of it :)
> 
> I rebase my 68000 tree on mainline regularly and make sure it still
> works. That's how I noticed and reported the above bug.
> I have a bunch of stuff that claude fable found, validated with QEMU
> and then I checked on real hardware but I'm not sure how to send that
> without it getting instantly marked as slop. :(

I didn't say anything about slop here, and in fact, _I_ have fixed up an
io_uring nommu bug in the past, using LLM tooling.  I am not objecting
to the use of that tool here at all, I am only commenting on the fact
that this bug has been present since 2020 without anyone noticing before
now, which implies a severe lack of users.

Heck, the out-of-tree ia64 developers report things faster than this :)

thanks,

greg k-h