[GIT PULL] TEE shared memory fix for 7.0

[GIT PULL] TEE shared memory fix for 7.0

[Jens Wiklander]

Hello arm-soc maintainers,

Please pull this patch removing the refcounting of kernel pages within
the TEE shared memory helper. 

Thanks,
Jens

The following changes since commit 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f:

  Linux 7.0-rc1 (2026-02-22 13:18:59 -0800)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/tee-fix-for-v7.0

for you to fetch changes up to 08d9a4580f71120be3c5b221af32dca00a48ceb0:

  tee: shm: Remove refcounting of kernel pages (2026-03-03 09:03:04 +0100)

----------------------------------------------------------------
TEE shared memory update for 7.0

Remove refcounting of kernel pages in register_shm_helper() to support
slab allocations.

----------------------------------------------------------------
Matthew Wilcox (1):
      tee: shm: Remove refcounting of kernel pages

 drivers/tee/tee_shm.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

Re: [GIT PULL] TEE shared memory fix for 7.0

[Krzysztof Kozlowski via OP-TEE]

On Mon, Mar 16, 2026 at 08:41:50AM +0100, Jens Wiklander wrote:
> Hello arm-soc maintainers,
> 
> Please pull this patch removing the refcounting of kernel pages within
> the TEE shared memory helper. 
> 
> Thanks,
> Jens
> 
> The following changes since commit 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f:
> 
>   Linux 7.0-rc1 (2026-02-22 13:18:59 -0800)
> 
> are available in the Git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/tee-fix-for-v7.0
> 
> for you to fetch changes up to 08d9a4580f71120be3c5b221af32dca00a48ceb0:
> 
>   tee: shm: Remove refcounting of kernel pages (2026-03-03 09:03:04 +0100)
> 
> ----------------------------------------------------------------
> TEE shared memory update for 7.0
> 
> Remove refcounting of kernel pages in register_shm_helper() to support
> slab allocations.

That's a supposed fix for a year old commit, not current RC, and the
commit msg does not explain what is the bug being fixed here. Looks like
it is doing improvement, not a fix. Can you provide here more
explanation of the actual bug being fixed to justify this going to
current RC fixes?

> 

Best regards,
Krzysztof

Re: [GIT PULL] TEE shared memory fix for 7.0

[Jens Wiklander]

Hi,

On Tue, Mar 17, 2026 at 9:51 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On Mon, Mar 16, 2026 at 08:41:50AM +0100, Jens Wiklander wrote:
> > Hello arm-soc maintainers,
> >
> > Please pull this patch removing the refcounting of kernel pages within
> > the TEE shared memory helper.
> >
> > Thanks,
> > Jens
> >
> > The following changes since commit 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f:
> >
> >   Linux 7.0-rc1 (2026-02-22 13:18:59 -0800)
> >
> > are available in the Git repository at:
> >
> >   git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/tee-fix-for-v7.0
> >
> > for you to fetch changes up to 08d9a4580f71120be3c5b221af32dca00a48ceb0:
> >
> >   tee: shm: Remove refcounting of kernel pages (2026-03-03 09:03:04 +0100)
> >
> > ----------------------------------------------------------------
> > TEE shared memory update for 7.0
> >
> > Remove refcounting of kernel pages in register_shm_helper() to support
> > slab allocations.
>
> That's a supposed fix for a year old commit, not current RC, and the
> commit msg does not explain what is the bug being fixed here. Looks like
> it is doing improvement, not a fix. Can you provide here more
> explanation of the actual bug being fixed to justify this going to
> current RC fixes?

I'm under the impression that it is a fix rather than an improvement.
However, since it has been stewing for a while, it's clearly not
urgent. I don't have anything specific on the bug fix, other than that
we're supposed to stop taking those refcounts. Perhaps Sumit, Marco,
or Matthew can add something?

Cheers,
Jens

Re: [GIT PULL] TEE shared memory fix for 7.0

[Marco Felsch]

On 26-03-17, Jens Wiklander wrote:
> Hi,
> 
> On Tue, Mar 17, 2026 at 9:51 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >
> > On Mon, Mar 16, 2026 at 08:41:50AM +0100, Jens Wiklander wrote:
> > > Hello arm-soc maintainers,
> > >
> > > Please pull this patch removing the refcounting of kernel pages within
> > > the TEE shared memory helper.
> > >
> > > Thanks,
> > > Jens
> > >
> > > The following changes since commit 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f:
> > >
> > >   Linux 7.0-rc1 (2026-02-22 13:18:59 -0800)
> > >
> > > are available in the Git repository at:
> > >
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/tee-fix-for-v7.0
> > >
> > > for you to fetch changes up to 08d9a4580f71120be3c5b221af32dca00a48ceb0:
> > >
> > >   tee: shm: Remove refcounting of kernel pages (2026-03-03 09:03:04 +0100)
> > >
> > > ----------------------------------------------------------------
> > > TEE shared memory update for 7.0
> > >
> > > Remove refcounting of kernel pages in register_shm_helper() to support
> > > slab allocations.
> >
> > That's a supposed fix for a year old commit, not current RC, and the
> > commit msg does not explain what is the bug being fixed here. Looks like
> > it is doing improvement, not a fix. Can you provide here more
> > explanation of the actual bug being fixed to justify this going to
> > current RC fixes?
> 
> I'm under the impression that it is a fix rather than an improvement.
> However, since it has been stewing for a while, it's clearly not
> urgent. I don't have anything specific on the bug fix, other than that
> we're supposed to stop taking those refcounts. Perhaps Sumit, Marco,
> or Matthew can add something?

It's a long outstanding fix regarding memory page management. The
userspace gets informed about this memory API misuse via a warning print
incl. a backtrace. This gets triggered only if userspace uses OP-TEE
trusted-keys or the OP-TEE EFI variables. Therefore I would like to get
it into 7.0 but 7.1 fine too.

Regards,
  Marco

> 
> Cheers,
> Jens
> 

-- 
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#CallMeByMyFirstName

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Re: [GIT PULL] TEE shared memory fix for 7.0

[Arnd Bergmann]

On Tue, Mar 17, 2026, at 13:53, Marco Felsch wrote:
> On 26-03-17, Jens Wiklander wrote:
>> 
>> I'm under the impression that it is a fix rather than an improvement.
>> However, since it has been stewing for a while, it's clearly not
>> urgent. I don't have anything specific on the bug fix, other than that
>> we're supposed to stop taking those refcounts. Perhaps Sumit, Marco,
>> or Matthew can add something?
>
> It's a long outstanding fix regarding memory page management. The
> userspace gets informed about this memory API misuse via a warning print
> incl. a backtrace. This gets triggered only if userspace uses OP-TEE
> trusted-keys or the OP-TEE EFI variables. Therefore I would like to get
> it into 7.0 but 7.1 fine too.

Yes, that is clearly a bugfix. I think we'd also want this to be
marked 'Cc: stable@vger.kernel.org' as it should also apply
to 6.18-LTS and 6.19. Greg tends to also pick up bugfixes that
don't have this, but it's generally better to be explicit here,
especially when it's not obvious what the impact of the fix is.

I've merge the pull request now. If you think this should be
in 6.18-lts and Greg doesn't pick it up by himself, maybe
let him know about it.

      Arnd

Re: [GIT PULL] TEE shared memory fix for 7.0

[Sumit Garg via OP-TEE]

On Wed, Mar 18, 2026 at 01:39:41PM +0100, Arnd Bergmann wrote:
> On Tue, Mar 17, 2026, at 13:53, Marco Felsch wrote:
> > On 26-03-17, Jens Wiklander wrote:
> >> 
> >> I'm under the impression that it is a fix rather than an improvement.
> >> However, since it has been stewing for a while, it's clearly not
> >> urgent. I don't have anything specific on the bug fix, other than that
> >> we're supposed to stop taking those refcounts. Perhaps Sumit, Marco,
> >> or Matthew can add something?
> >
> > It's a long outstanding fix regarding memory page management. The
> > userspace gets informed about this memory API misuse via a warning print
> > incl. a backtrace. This gets triggered only if userspace uses OP-TEE
> > trusted-keys or the OP-TEE EFI variables. Therefore I would like to get
> > it into 7.0 but 7.1 fine too.
> 
> Yes, that is clearly a bugfix. I think we'd also want this to be
> marked 'Cc: stable@vger.kernel.org' as it should also apply
> to 6.18-LTS and 6.19. Greg tends to also pick up bugfixes that
> don't have this, but it's generally better to be explicit here,
> especially when it's not obvious what the impact of the fix is.
> 
> I've merge the pull request now. If you think this should be
> in 6.18-lts and Greg doesn't pick it up by himself, maybe
> let him know about it.

Thanks Arnd for picking up this fix. Last week I was on business travel
hence the delay in my response. I see Sasha already picked it up for
backports.

-Sumit