Re: [PATCH v3 1/2] arm64: pageattr: Use pagewalk API to change memory permissions

[Dev Jain]

On 14/06/25 8:20 pm, Karim Manaouil wrote:
> On Fri, Jun 13, 2025 at 05:27:27PM +0100, Lorenzo Stoakes wrote:
> > On Fri, Jun 13, 2025 at 07:13:51PM +0530, Dev Jain wrote:
> > > +		if (WARN_ON_ONCE((next - addr) != PGDIR_SIZE))
> > > +			return -EINVAL;
> > I guess the point here is to assert that the searched range _entirely
> > spans_ the folio that the higher order leaf page table entry describes.
> >
> > I'm guessing this is desired.
> >
> > But I'm not sure this should be a warning?
> >
> > What if you happen to walk a range that isn't aligned like this?
> My understandging is that the caller must ensure that addr is
> pud/pmd/pte-aligned. But, imho, since -EINVAL is returned, I don't think
> the WARN_ON_ONCE() is needed.

I don't really have a strong opinion on this. Ryan may be better fitted
to answer.

>