Removing __get_user / __put_user for good

Removing __get_user / __put_user for good

[Linus Torvalds]

Bah. I made this branch of mine public because I wanted Michael
Tsirkin to check the vhost part.

But honestly, the i915 side and the coco/SEV patches are the much more
interesting ones.

So this brings in some new victims^Hpeople for that git branch to comment on.

It's all in

  git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
uaccess-cleanup

I haven't dared actually boot it yet.

                    Linus

On Mon, 19 Oct 2026 at 20:51, Linus Torvalds
<torvalds@linuxfoundation.org> wrote:
>
> I have a whole branch that removes __get_user() and __put_user() entirely.
>
> Somebody should check that I did it right. But I didn't want to do the
> pagefault_disable() around the vringh_notify() part, so it's not quite
> the same as yours.
>
> Let me just push it out. I was going to let it simmer, but your email
> made me go "I should just let more people look at it".
>
> Mind taking a look at the 'uaccess-cleanups' branch?
>
> It builds for me. That's all the testing it has gotten so far. Blush.
>
>                    Linus

Re: Removing __get_user / __put_user for good

[Jani Nikula]

On Mon, 19 Oct 2026, Linus Torvalds <torvalds@linuxfoundation.org> wrote:
> Bah. I made this branch of mine public because I wanted Michael
> Tsirkin to check the vhost part.
>
> But honestly, the i915 side and the coco/SEV patches are the much more
> interesting ones.
>
> So this brings in some new victims^Hpeople for that git branch to comment on.
>
> It's all in
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> uaccess-cleanup
>
> I haven't dared actually boot it yet.

I rebased it on top of our development branch and sent it to i915
CI. Let's see if it blows up. ;)


BR,
Jani.


-- 
Jani Nikula, Intel

Re: Removing __get_user / __put_user for good

[Michael S. Tsirkin]

On Mon, Oct 19, 2026 at 09:25:02PM -1000, Linus Torvalds wrote:
> Bah. I made this branch of mine public because I wanted Michael
> Tsirkin to check the vhost part.
> 
> But honestly, the i915 side and the coco/SEV patches are the much more
> interesting ones.
> 
> So this brings in some new victims^Hpeople for that git branch to comment on.
> 
> It's all in
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> uaccess-cleanup
> 
> I haven't dared actually boot it yet.
> 
>                     Linus

vpda seems to survive light testing in a VM for me.

Tested-by: Michael S. Tsirkin <mst@redhat.com>


It's still buggy if there is a swapout right before
the access, just like it was previously, but hey.
One splat less. An improvement.

You might want:

Fixes: 42823a871fd4 ("vringh: support VA with iotlb")

with that, vdpa/vhost bits:

Acked-by: Michael S. Tsirkin <mst@redhat.com>



> On Mon, 19 Oct 2026 at 20:51, Linus Torvalds
> <torvalds@linuxfoundation.org> wrote:
> >
> > I have a whole branch that removes __get_user() and __put_user() entirely.
> >
> > Somebody should check that I did it right. But I didn't want to do the
> > pagefault_disable() around the vringh_notify() part, so it's not quite
> > the same as yours.
> >
> > Let me just push it out. I was going to let it simmer, but your email
> > made me go "I should just let more people look at it".
> >
> > Mind taking a look at the 'uaccess-cleanups' branch?
> >
> > It builds for me. That's all the testing it has gotten so far. Blush.
> >
> >                    Linus

Re: Removing __get_user / __put_user for good

[Ingo Molnar]

* Linus Torvalds <torvalds@linuxfoundation.org> wrote:

> Bah. I made this branch of mine public because I wanted Michael
> Tsirkin to check the vhost part.
> 
> But honestly, the i915 side and the coco/SEV patches are the much more
> interesting ones.
> 
> So this brings in some new victims^Hpeople for that git branch to comment on.
> 
> It's all in
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> uaccess-cleanup

So it's 'uaccess-cleanups', plural, in case someone copy & pasted
this URI verbatim instead of using the branch name from your
earlier mail. :-)

All the x86 cleanups look good to me in principle, and a quick
test-build & boot shows no problems (both on 64-bit and 32-bit),
but regular testing doesn't fully excercise the exception paths
of these changes, so YMMV.

( BTW., there's a new dependency introduced by this series,
  if an architecture gets rid of __get_user(), then it must
  define arch_get_kernel_nofault(), otherwise it will gain
  new uses of __get_user()/__put_user() via the generic implementations
  of __get_kernel_nofault() and __put_kernel_nofault(). No big deal
  I suppose. )

Thanks,

	Ingo