Re: Improving Linux Commit Backporting

[Sasha Levin <sashal@kernel.org>]

On Thu, Apr 03, 2025 at 03:51:25PM +0100, gregkh@linuxfoundation.org wrote:
>On Thu, Apr 03, 2025 at 02:57:34PM +0100, gregkh@linuxfoundation.org wrote:
>> On Thu, Apr 03, 2025 at 02:45:35PM +0100, gregkh@linuxfoundation.org wrote:
>> > On Thu, Apr 03, 2025 at 01:15:28PM +0000, Manthey, Norbert wrote:
>> > > Dear Linux Stable Maintainers,
>> > >
>> > > while maintaining downstream Linux releases, we noticed that we have to
>> > > backport some patches manually, because they are not picked up by your
>> > > automated backporting. Some of these backports can be done with
>> > > improved cherry-pick tooling. We have implemented a script/tool "git-
>> > > fuzzy-pick" which we would like to share. Besides picking more commits,
>> > > the tool also supports executing a validation script right after
>> > > picking, e.g. compiling the modified source file. Picking stats and
>> > > details are presented below.
>> > >
>> > > We would like to discuss whether you can integrate this improved tool
>> > > into into your daily workflows. We already found the stable-tools
>> > > repository [1] with some scripts that help automate backporting. To
>> > > contribute git-fuzzy-pick there, we would need you to declare a license
>> > > for the current state of this repository.
>> >
>> > There's no need for us to declare the license for the whole repo, you
>> > just need to pick a license for your script to be under.  Anything
>> > that's under a valid open source license is fine with me.
>> >
>> > That being said, I did just go and add SPDX license lines to all of the
>> > scripts that I wrote, or that was already defined in the comments of the
>> > files, to make it more obvious what they are under.
>>
>> Wait, you should be looking at the scripts in the stable-queue.git tree
>> in the scripts/ directory.  You pointed at a private repo of some things
>> that Sasha uses for his work, which is specific to his workflow.
>
>Also, one final things.  Doing backports to older kernels is a harder
>task than doing it for newer kernels.  This means you need to do more
>work, and have a more experienced developer do that work, as the nuances
>are tricky and slight and they must understand the code base really
>well.
>
>Attempting to automate this, and make it a "junior developer" task
>assignment is ripe for errors and problems and tears (on my side and
>yours.)  We have loads of examples of this in the past, please don't
>duplicate the errors of others and think that "somehow, this time it
>will be different!", but rather "learn from our past mistakes and only
>make new ones."
>
>Good luck with backporting, as I know just how hard of a task this
>really is.  And obviously, you are learning that too :)

I've played with wiggle[1] in the past, which does all what you've
described and more.

It introduced too many issues, where it wasn't worth doing it. I really
think that the better solution here is to figure out dependencies and
bring them in.

I'd advise against using such tool at the scale of -stable :)

[1] https://github.com/neilbrown/wiggle

-- 
Thanks,
Sasha