Re: [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation

[Kees Cook]

On January 19, 2026 8:00:00 AM PST, Dave Hansen <dave.hansen at intel.com> wrote:
>On 1/19/26 05:01, Ryan Roberts wrote:
>> x86 (AWS Sapphire Rapids):
>> +-----------------+--------------+-------------+---------------+
>> | Benchmark       | Result Class |   v6.18-rc5 | per-task-prng |
>> |                 |              | rndstack-on |               |
>> |                 |              |             |               |
>> +=================+==============+=============+===============+
>> | syscall/getpid  | mean (ns)    |  (R) 13.32% |     (R) 4.60% |
>> |                 | p99 (ns)     |  (R) 13.38% |    (R) 18.08% |
>> |                 | p99.9 (ns)   |      16.26% |    (R) 19.38% |
>
>Like you noted, this is surprising. This would be a good thing to make
>sure it goes in very early after -rc1 and gets plenty of wide testing.

Right, we are pretty late in the dev cycle (rc6). It would be prudent to get this into -next after the coming rc1 (1 month from now).

On the other hand, the changes are pretty "binary" in the sense that mistakes should be VERY visible right away. Would it be better to take this into -next immediately instead?

>But I don't see any problems with the approach, and the move to common
>code looks like a big win as well:

Agreed; I think it's looking great.

-- 
Kees Cook