Re: [PATCH 17/30] mm: prefer vma_[start,end]_pgoff() to vma->vm_pgoff in kernel/

[Lorenzo Stoakes <ljs@kernel.org>]

On Thu, Jul 09, 2026 at 11:49:18AM -0400, Gregory Price wrote:
> On Thu, Jul 02, 2026 at 12:30:59PM +0100, Lorenzo Stoakes wrote:
> >
> ...
> > static inline unsigned long vma_offset(const struct vm_area_struct *vma,
> > 				       const unsigned long address)
> > {
> > 	/* Retains page offset and tags. */
> > 	return address - vma->vm_start;
> > }
> >
> ...
> > And I'm not sure it's really all that useful. Perhaps retaining vma_offset()
> > would be though.
> >
>
> Silly question:

There's no such thing :)

>
>    What's the purpose of retaining tags in a non-address value?

Well if you want to reconstitute an address from it later then that'd be the
intent, but I'm being hand wavey here for sure.

Main thing is to retain stuff under the page mask

>
> That sounds like there's fragility just waiting to be broken.
>
> (I presume you are talking about things like ARM MTE and such, right?)
>
> > This is one that I think makes more sense.
> >
> > But in general, I'd rather hold off from yet more churn here.
> >
> > I'm making these changes to establish a basis for virtual page offsets
> > introduced in [0], rather than just cleaning up in general.
> >
>
> I agree with this.  If the refactors here suddenly have to think about
> corner cases on things like tags, that's better resolved separately.

Yeah this series is huge enough as it is :P

>
> ~Gregory

Cheers, Lorenzo