Re: [PATCH] userfaultfd: hugetlbfs: add UFFDIO_COPY support for shared mappings

From: Kirill A. Shutemov
Date: Thu Feb 23 2017 - 09:56:32 EST

On Wed, Feb 22, 2017 at 04:15:07PM +0100, Andrea Arcangeli wrote:
> On Tue, Feb 21, 2017 at 04:25:45PM +0300, Kirill A. Shutemov wrote:
> > I think more strict vma_is_anonymous() is a good thing.
> >
> > But I don't see a point introducing one more helper. Let's just make the
> > existing helper work better.
> That would be simpler agreed. The point of having an "unsafe" faster
> version was only for code running in page fault context where the
> additional check is unnecessary.

Well, I don't think that the cost of additional check is significant here.
And we can bring ->vm_ops a bit closer to ->vm_flags to avoid potential
cache miss.

Kirill A. Shutemov