Re: [PATCH 6.12.y 4/4] crypto: x86/aegis - Fix sleeping when disallowed on PREEMPT_RT

[Sasha Levin <sashal@kernel.org>]

On Thu, Aug 21, 2025 at 11:39:51PM -0400, Eric Biggers wrote:
>On Thu, Aug 21, 2025 at 11:28:56PM -0400, Sasha Levin wrote:
>> On Thu, Aug 21, 2025 at 11:23:04PM -0400, Eric Biggers wrote:
>> > On Thu, Aug 21, 2025 at 11:06:17PM -0400, Sasha Levin wrote:
>> > > From: Eric Biggers <ebiggers@kernel.org>
>> > >
>> > > [ Upstream commit c7f49dadfcdf27e1f747442e874e9baa52ab7674 ]
>> > >
>> > > skcipher_walk_done() can call kfree(), which takes a spinlock, which
>> > > makes it incorrect to call while preemption is disabled on PREEMPT_RT.
>> > > Therefore, end the kernel-mode FPU section before calling
>> > > skcipher_walk_done(), and restart it afterwards.
>> > >
>> > > Moreover, pass atomic=false to skcipher_walk_aead_encrypt() instead of
>> > > atomic=true.  The point of atomic=true was to make skcipher_walk_done()
>> > > safe to call while in a kernel-mode FPU section, but that does not
>> > > actually work.  So just use the usual atomic=false.
>> > >
>> > > Fixes: 1d373d4e8e15 ("crypto: x86 - Add optimized AEGIS implementations")
>> > > Cc: stable@vger.kernel.org
>> > > Signed-off-by: Eric Biggers <ebiggers@kernel.org>
>> > > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>> > > Signed-off-by: Sasha Levin <sashal@kernel.org>
>> > > ---
>> > >  arch/x86/crypto/aegis128-aesni-glue.c | 8 ++++++--
>> > >  1 file changed, 6 insertions(+), 2 deletions(-)
>> >
>> > 1. Missing Cc of the relevant mailing lists
>> > 2. Missing cover letter
>>
>> This was sent following the instructions in the FAILED: email generated by
>> Greg. If you feel its insufficient, take it up with him.
>
>You're one of the stable maintainers.  You can't just deflect and claim
>this is not your problem.

We perform different parts of the process. I don't send FAILED: mails out, I
don't have control over what Greg sends out. If you feel that the recipient
list is insufficient then Greg should be in the loop - don't take it out on me.

These mails looked the same for years (decade+?), if for some reason you think
that a cover letter or an expanded cc list would be useful to have, then you
can just suggest it - no need to berate me for not sending one.

>> > 3. Missing base-commit, and doesn't apply to stable/linux-6.16.y
>>
>> As the subject line indicates, this applies on 6.12, not 6.16.
>>
>> > 4. Two different series were sent out, both containing this patch
>>
>> You might have missed that they're for different trees?
>>
>
>Sorry, I meant to write 6.12.  6.12 was indeed what I tried to apply it
>to, and it failed.  And there are two series for 6.12, see
>https://lore.kernel.org/stable/20250822030632.1053504-4-sashal@kernel.org
>and
>https://lore.kernel.org/stable/20250822030617.1053172-4-sashal@kernel.org/

Yup, those are replies to two different FAILED emails for two different
patches that failed to backport.

Could you share the conflict you've observed? Both series applied cleanly to
stable/linux-6.12.y for me.

>They were sent only 14 seconds apart, so these submissions appear to be
>automated.

Not too automated :)

I fix up the backports, run builds, and go do something else.

When I get back to the computer, if the builds passed, I just send out the mails.

-- 
Thanks,
Sasha