linux-kernel - Re: [PATCH 5.4 063/355] powerpc/kvm: Fix kvm_use_magic

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Date:   Tue, 16 Nov 2021 15:15:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Andreas Gruenbacher <agruenba@...hat.com>
Cc:     Sasha Levin <sashal@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        Mathieu Malaterre <malat@...ian.org>,
        Paul Mackerras <paulus@...abs.org>, kvm-ppc@...r.kernel.org
Subject: Re: [PATCH 5.4 063/355] powerpc/kvm: Fix kvm_use_magic_page

On Tue, Nov 16, 2021 at 03:00:19PM +0100, Andreas Gruenbacher wrote:
> On Tue, Nov 16, 2021 at 2:57 PM Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> > On Tue, Nov 16, 2021 at 02:54:10PM +0100, Andreas Gruenbacher wrote:
> > > On Tue, Nov 16, 2021 at 1:54 AM Sasha Levin <sashal@...nel.org> wrote:
> > > > On Mon, Nov 15, 2021 at 06:47:41PM +0100, Andreas Gruenbacher wrote:
> > > > >Greg,
> > > > >
> > > > >On Mon, Nov 15, 2021 at 6:10 PM Greg Kroah-Hartman
> > > > ><gregkh@...uxfoundation.org> wrote:
> > > > >> From: Andreas Gruenbacher <agruenba@...hat.com>
> > > > >>
> > > > >> commit 0c8eb2884a42d992c7726539328b7d3568f22143 upstream.
> > > > >>
> > > > >> When switching from __get_user to fault_in_pages_readable, commit
> > > > >> 9f9eae5ce717 broke kvm_use_magic_page: like __get_user,
> > > > >> fault_in_pages_readable returns 0 on success.
> > > > >
> > > > >I've not heard back from the maintainers about this patch so far, so
> > > > >it would probably be safer to leave it out of stable for now.
> > > >
> > > > What do you mean exactly? It's upstream.
> > >
> > > Mathieu Malaterre broke this test in 2018 (commit 9f9eae5ce717) but
> > > that wasn't noticed until now (commit 0c8eb2884a42). This means that
> > > this fix probably isn't critical, so I shouldn't be backported.
> >
> > Then why did you tag it to be explicitly backported to all stable
> > kernels newer than 4.18?
> 
> Well, sorry for that. What else do you expect me to do in addition to
> pointing out the mistake?

Ah, I think we are misunderstanding each other here.  I will go drop it,
but in the future maybe "hey, I didn't mean to mark this for stable, can
you please drop it?" might be a bit more direct and too the point.
Otherwise we are all confused here...

thanks,

greg k-h