Re: [PATCH v1 06/11] mm: support GUP-triggered unsharing via FAULT_FLAG_UNSHARE (!hugetlb)

[Linus Torvalds]

On Fri, Dec 17, 2021 at 7:30 PM Nadav Amit <namit@xxxxxxxxxx> wrote:
>
> In such a case, I do think it makes sense to fail uffd-wp (when
> page_count() > 1), and in a prototype I am working on I do something
> like that.

Ack. If uddf-wp finds a page that is pinned, just skip it as not
write-protectable.

Because some of the pinners might be writing to it, of course - just
not through the page tables.

So that sounds like the right thing to do. I _think_ we discussed this
the last time this came up. I have some dim memory of that. Jason,
ring a bell?

             Linus