Re: [PATCH v2 1/2] vdso: move offset_in_page() from linux/mm.h to vdso/page.h

[Lorenzo Stoakes <ljs@kernel.org>]

On Thu, May 21, 2026 at 09:34:57PM +0300, Andy Shevchenko wrote:
> On Thu, May 21, 2026 at 4:56 PM Lorenzo Stoakes <ljs@kernel.org> wrote:
> > On Thu, May 21, 2026 at 12:16:00PM +0100, Lorenzo Stoakes wrote:
> > > On Thu, May 21, 2026 at 11:06:57AM +0200, Thorsten Blum wrote:
>
> ...
>
> > Unless a series can be put forwards that sensibly justifies this, not some
> > random change somewhere, I'd rather we not take it.
>
> The problem is not only a compile time but more generic - the mess in
> the Linux headers. People who want to use this match need to include
> mm.h which is a bloated header with *tons* of unneeded dependencies
> (for those pure users) and increases chaos in how the headers are
> split.

No question the headers are a bit of a mess, and I've had absolute headaches
with dependency chain stuff there.

> If we don't care about it, then provide an "INCLUDE EVERYTHING" header

That's a false dichotomy - the series isn't upstreamable as-is. I've provided
feedback that's not been addressed so we won't take it.

> and let the driver just include that. But of course, we don't do that,
> we do modular headers for a reason. Currently I see no reason to have
> that simple helper to be mm.h as its use is much wider in the cases
> where the whole hell of mm.h is not needed.

We also don't want to have wildly divergent overly-specific individual headers,
and series have to be upstreamable.

>
> So, the best course of actions I see now is leave mm people alone and
> simply duplicate what we need in the headers we want to see
> (util_macros.h as a rough approximation, but maybe something better).

I mean I feel engaging civilly and constructively with people who have taken
their time out to provide feedback is a better approach, but obviously what you
do elsewhere in the kernel is up to you.

>
>
> > Also vdso/page.h is a VDSO-specific header by MAINTAINERS, offset_in_page() is
> > really an mm thing so that's another reason not to move it.
> >
> > (A justifying change would show actually build time/binary bloat/etc. numbers +
> > involve actual substantive changes).
>
>
>
> --
> With Best Regards,
> Andy Shevchenko

Overall this all feels like a storm in a teapot, this is a very trivial macro
and the use case seems nebulous at best.

A series actually addressing header issues with _a justifying reason provided_
(I am astonished that it still hasn't!), would be more useful, as long as it was
upstreamable and didn't cause other issues.

We in mm are friendly and accepting of good series, engaging positively will get
a positive reception :)

Thanks, Lorenzo