On Thu, 15 Sep 2022, Jann Horn wrote:
> On Thu, Sep 15, 2022 at 1:01 PM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Thu, Sep 15, 2022 at 12:48:44PM +0200, Jann Horn wrote:
> > > Hi!
> > >
> > > Hugh reached out to me and let me know (in nicer words) that I botched
> > > my attempt to re-implement b67fbebd4cf9 for the stable backport; the
> > > backport is an incomplete fix (because I forgot that in
> > > unmap_region(), "vma" is just one of potentially several VMAs).
> > >
> > > What should the commit message for fixing that look like? And should
> > > we first revert the botched backport and then do a correct backport on
> > > top of that, or should I write a single fix commit?
> >
> > Which every you want is fine with me, I can easily add 1 or 2 patches :)
> >
> > If you want do the revert now, and get a release out with that, and then
> > do a "better" patch later, that's fine too, just let me know what you
> > want to do.
>
> Ok, I just sent you a fixup patch that should apply cleanly to the
> affected stable trees ("[PATCH stable 4.9-5.15] mm: Fix TLB flush for
> not-first PFNMAP mappings in unmap_region()").
>
> @Hugh: Can you maybe take a look and let me know if this looks reasonable now?
Yes, that one looks fine to me, thanks Jann. I would not have liked it
if Peter had chosen that way for upstream, but there's good reason to
avoid using tlb_end_vma() in these backports, and good reason to avoid
cluttering up free_pgtables(). No way great: this way good enough, thanks.
Hugh
