Re: Introduce Sashiko (agentic review of Linux kernel changes)

[Roman Gushchin <roman.gushchin@linux.dev>]

SeongJae Park <sj@kernel.org> writes:

> Hello Roman,
>
> On Tue, 17 Mar 2026 15:31:11 +0000 Roman Gushchin <roman.gushchin@linux.dev> wrote:
>
>> Hello,
>> 
>> I'm happy to share something my colleagues and I have been working on
>> for the last several months:
>> Sashiko - an agentic system for Linux kernel changes.
>> 
>> First, Sashiko is available as a service at:
>>   * https://sashiko.dev
>
> Great work.  Thank you!
>
> There are many similar tools but this is the first free web service I know.
> I'm still feeling uncomfortable or not prepared for running some AI tools on my
> own.  Therefore I was only waiting for some nice people sharing their AI review
> results (some people including Chris Mason did, and it was really helpful,
> thanks again), or the arrival of this kind of public and just working service.
> This feels like the chat-gpt moment to me.

Thank you!

>> 
>> It reviews all patches sent to LKML and several other Linux kernel
>> mailing lists using the Gemini 3.1 Pro model.
>> 
>> I want to thank my employer, Google, for providing the ML compute
>> resources and infrastructure for making this project real.
>> 
>> Sashiko is written in Rust from scratch, mostly using Gemini CLI. It's
>> fully self-contained and does not rely on any CLI coding tools. It
>> supports various LLMs (at this moment mostly tested with Gemini
>> Pro/Flash and slightly with Claude).
>> 
>> And finally it's fully open-source:
>>   * https://github.com/sashiko-dev/sashiko
>
> Awesome.  I'm still feeling uncomfortable or not prepared to running some AI
> tools on my own.  But I will try to find ways to contribute.
>
>> 
>> It's licensed under the Apache-2.0 License, and the ownership of the
>> project was transferred to the Linux Foundation. Contributions are
>> really welcome using DCO.
>> 
>> Sashiko is based on a set of open-source prompts initially developed by
>> Chris Mason:
>>   * https://github.com/masoncl/review-prompts/
>
> Kudos to Chris!
>
>> 
>> But Sashiko leverages a different multi-stage review protocol, which
>> somewhat mimics the human review process and forces the LLM to look at
>> the proposed change from different angles.
>> 
>> In my measurement, Sashiko was able to find 53% of bugs based
>> on a completely unfiltered set of 1,000 recent upstream issues using
>> "Fixes:" tags (using Gemini 3.1 Pro). Some might say that 53% is not
>> that impressive, but 100% of these issues were missed by human reviewers.
>> Also, many of these issues (like tricky build failures, performance
>> problems, etc) are very hard/impossible to spot from reviewing the code,
>> so arguably 100% is not reachable. We started with low 30's a couple of
>> months ago; better models and improvements in the review protocol and
>> subsystem prompts pushed it to low 50's. With better LLMs and collective
>> effort on prompts we can push even further.
>> 
>> Measuring false positives is much harder, but based on manual reviews of
>> reviews, it's pretty good: it's rarely dead wrong, but sometimes it can
>> nitpick or find too many low-value issues. In many cases, it can be
>> improved with prompt engineering.
>> 
>> * What's next?
>> 
>> This is our first version and it's obviously not perfect. There is a
>> long list of fixes and improvements to make. Please, don't expect it to
>> be 100% reliable, even though we'll try hard to keep it up and running.
>> Please use github issues or email me any bug reports and feature
>> requests, or send PR's.
>> 
>> As of now, Sashiko only provides a web interface;
>> however, Konstantin Ryabitsev is already adding sashiko.dev support to b4,
>> and SeongJae Park is adding support to hkml.
>> That was really fast, thank you!
>
> hkml support was available owing to Sashiko providing the decent API, and b4's
> use of it is open source.  Kudos to Sashiko team and Konstantin.  I'm planning
> to make more integration into hkml, for my workflow and based on other hkml
> user feedback.

Thank you for doing this!

>> 
>> We're working on adding an email interface to Sashiko, and soon Sashiko
>> will be able to send out reviews over email - similar to what the bpf
>> subsystem already has. It will be opt-in by subsystem and will have options
>> to CC only the author of the patch, maintainers, volunteers, or send a
>> fully public reply. If you're a maintainer and have a strong preference
>> to get reviews over email, please let me know.
>
> I, as the maintainer of DAMON subsystem (damon@lists.linux.dev), do have a
> strong preference to get reviews over email for all patches that sent to the
> mailing list.  I'm already manually doing that.  I'm planning to extend hkml
> for doing this easier.  It would be nice and efficient if Sashiko can do this
> on its own.

Noted. I'll enable it as soon as we'll have it.

>
>> 
>> We also desperately need better benchmarks, especially when it comes to
>> false positives. Having a decent vetted set of officially perfect
>> commits can help with this.
>
> I'm also curious if there is a public channel for giving feedback about the
> reviews.  As you mentioned above, Sashiko sometimes says something that is not
> technically correct.  I'm wondering if there is a way to let Sashiko knows such
> things for improvement.

As of now, I suggest using Github issues. Later on, you could simple
reply to Sashiko's emails.

But also realistically I likely won't be able to look into every single
false positive, so I'd really appreciate some initial analysis: e.g. if
there is a common pattern or a number of similar reviews with the same
problem.

>> 
>> Finally, some subsystems have a good prompts coverage and some don't. It
>> doesn't have to be lengthy documentation (and it might actually be
>> counter-productive), but having a small list of things to look at - some
>> high-level concepts which are hard to grasp from the code, etc. - can
>> help a lot with both bug discovery and false positives.
>
> I found there is no prompt for DAMON.  I'm still convinced with Sashiko's
> current review, and have no idea for DAMON-custom prompts.  So that's fine for
> now.  I will consider adding something if I get some idea, though.

My suggestion is to read through a number of DAMON-specific reviews and
see if there are any common patterns of false positives or missed
errors. Once you have a feeling like "Damn, Sashiko doesn't really
understand X about the DAMON!" then you put it into the prompt.

Thanks!