Re: [tip: x86/urgent] x86/mm/pat: Acquire init_mm write lock on collapse to avoid UAF

[Lorenzo Stoakes (ARM)]

On Tue, Sep 08, 2026 at 12:32:17PM +0300, Mike Rapoport wrote:
> On Tue, Sep 01, 2026 at 04:36:38PM -0700, Dave Hansen wrote:
> > On 9/1/26 00:10, Lorenzo Stoakes (ARM) wrote:
> > > Dave - you've somehow applied this patch completely incorrectly to x86/urgent,
> > > I'm not happy with this going to Linus in this form :/
> >
> > Me neither, btw.
> >
> > So, here it is applied:
> >
> > > https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=cpa1
> >
> > The diffstat exactly matches the mbox that I sucked in. I'm going to
> > launch some tests overnight.
> >
> > The only things I really munged were a little merge issue with patch 1,
> > a SoB ordering issue in patch 3, and a few scattered rewordings in the
> > commit messages.
> >
> > Not pushed to x86/urgent, yet.
>
> I have to say I'm confused with today's batch of tip-bot emails saying Ingo
> applied these to x86/mm :/

Since I don't seem to get replies to mails on this topic, I can only
_guess_ :), but:

* I see patches in x86/urgent that aren't in x86/mm, so that rules out
  x86/mm being a stepping stone in the process.

* x86/urgent has had more patches added to it, for series sent after this
  one, which fix bugs from 2024, 2025 etc. So that's all working as
  expected.

* We've already highlighted that this series fixes bugs users are seeing in
  production, so I don't see why it'd be deprioritised.

* It's coming form a private dev repo/branch so I can't imagine it's a
  wayward script (but maybe?)

* The patches have been in linux-next for a while (maybe Dave/Ingo wanted
  them there longer? They were there for weeks before the ->x86 stuff
  though).

Perhaps the reported bug that you've now fixed was the hold up? I guess who
knows :)

So yeah, I'm also rather confused :)

Ah well.

I guess taking them through the mm tree wouldn't really be sensible/the
right thing to do at this stage, so I guess let's hope they land for 7.4.

>
> --
> Sincerely yours,
> Mike.

--
Cheers, Lorenzo