On 3/1/19 8:59 AM, Catalin Marinas wrote:

quoted

quoted

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?

Most callers of find_vma*() always follow it by a check of
vma->vma_start against some tagged address ('end' in the
userfaultfd_(un)register()) case. So it's not sufficient to untag it in
find_vma().

If that's truly the common case, sounds like we should have a find_vma()
that does the vma_end checking as well.  Then at least the common case
would not have to worry about tagging.

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