Re: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock

Marc Zyngier
2024-08-06T08:56:05Z

On Tue, 06 Aug 2024 00:26:54 +0100,
Oliver Upton <oliver.upton@linux.dev> wrote:
>
> On Mon, Aug 05, 2024 at 11:26:03PM +0000, Oliver Upton wrote:
> > [+cc Fuad]
>
> Take 2!
>
> > Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting
> > the page as dirty out of the critical section") that restructuring
> > around the MMU lock was helpful for reuse (presumably for pKVM), but I
> > lack the context there.
> >
> > On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote:
> > > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a
> > > page/folio dirty after it has been written back can make some filesystems
> > > unhappy (backing KVM guests will such filesystem files is uncommon, and
> >
> > typo: s/will/with/
> >
> > > the race is minuscule, hence the lack of complaints). See the link below
> > > for details.

Should we consider reverting 9c30fc615daa then?

Thanks,

M.

--
Without deviation from the norm, progress is not possible.