Re: [RFC PATCH v3 0/5] mm, bpf: BPF based THP adjustment

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Tue, Jul 22, 2025 at 08:02:15PM +0800, Yafang Shao wrote:
> On Tue, Jul 22, 2025 at 7:55 PM Lorenzo Stoakes
> > >
> > > While this is not a strict requirement—maintainers can remove kfuncs
> > > immediately without deprecation—following this guideline helps avoid
> > > unnecessary disruptions for users.
> >
> > The documentation doesn't state this, you are surely just inferring it?
>
> As noted in the other thread, the maintainers ultimately have final
> say on this matter. I'm simply sharing my perspective here.

Sure, sorry, I was probably being a bit too succinct in my reply here :P
see other thread, I think the situation won't necessarily be quite as clear
in practice.

>
> >
> > >
> > > --
> > > Regards
> > > Yafang
> >
> > Overall I think we need a different mechanism in addition to this, such as
> > a very clearly described CONFIG_ option that makes it ABUNDANTLY clear that
> > the config and thus the related BPF hook may be removed at any time.
> >
> > Ideally with 'experimental' or such in the name, or perhaps even tainting
> > the kernel.
>
> Agreed.

Thanks, discussed in other thread also.

>
> >
> > We definitely need something better than what this documentation is saying,
> > sorry. I am not in any way confident in relying no what this document
> > states.
>
> The documentation has always been difficult to understand ;-)

:) I think it is being rather too cautious or really circumspect in its
wording, and could do with being a lot more direct, in my view.

But I suppose since organising kernel developers into agreeing on something
is like herding cats, it might be difficult to get agreement to the point
where the documentation could really be that.

>
> --
> Regards
> Yafang

Cheers, Lorenzo