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

[Linus Torvalds]

On Thu, Jan 7, 2021 at 2:31 PM Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
>
> Random memory corruption will still silently materialize as result of
> the speculative lookups in the above scenario.

Explain.

Yes, you'll get random memory corruption if you keep doing wrprotect()
without mmap_sem held for writing.

But I thought we agreed earlier that that is a bug. And I thought the
softdirty code already got it for writing.

           Linus