Re: [patch 05/16] mm: Allow special mappings with user access cleared

From: Peter Zijlstra
Date: Wed Dec 13 2017 - 10:06:46 EST


On Wed, Dec 13, 2017 at 04:00:07PM +0100, Peter Zijlstra wrote:
> On Wed, Dec 13, 2017 at 05:43:39PM +0300, Kirill A. Shutemov wrote:
> > > am I perchance looking at the wrong tee?
> >
> > I'm looking at Linus' tree.
>
> Clearly I'm not synced up enough... :/
>
> > It was changed recently:
> > 5c9d2d5c269c ("mm: replace pte_write with pte_access_permitted in fault + gup paths")
> >
>
> Indeed. So FOLL_GET should also get these tests and, as you said, the
> other levels too.
>
> I would like FOLL_POPULATE (doesn't have FOLL_GET) to be allowed
> 'access'.

Similarly, should we avoid arch_vma_access_permitted() if !FOLL_GET ?