Re: [PATCH 2/2] mm: soft_dirty: userfaultfd: introduce wrprotect_tlb_flush_pending

Linus Torvalds
2021-01-08T19:26:38Z

On Fri, Jan 8, 2021 at 9:53 AM Andrea Arcangeli <aarcange@redhat.com> wrote:
>
> Do you intend to eventually fix the zygote vmsplice case or not?
> Because in current upstream it's not fixed currently using the
> enterprise default config.

Is this the hugepage case? Neither of your patches actually touched
that, so I've forgotten the details.

> Irrelevant special case as in: long term GUP pin on the memory?

Irrelevant special case in that

(a) an extra COW shouldn't be a correctness issue unless somebody
does something horribly wrong (and obviously the code that hasn't
taken the mmap_lock for writing are then examples of that)

and

(b) it's not a performance issue either unless you can find a real
load that does it.

Hmm?

Linus