Re: [PATCH v10 07/12] fs, arm64: untag user pointers in fs/userfaultfd.c

[Andrey Konovalov]

On Sat, Feb 23, 2019 at 12:06 AM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> On 2/22/19 4:53 AM, Andrey Konovalov wrote:
> > userfaultfd_register() and userfaultfd_unregister() use provided user
> > pointers for vma lookups, which can only by done with untagged pointers.
>
> So, we have to patch all these sites before the tagged values get to the
> point of hitting the vma lookup functions.  Dumb question: Why don't we
> just patch the vma lookup functions themselves instead of all of these
> callers?

That might be a working approach as well. We'll still need to fix up
places where the vma fields are accessed directly. Catalin, what do
you think?