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Date: Wed, 6 Jan 2016 13:31:55 +0000
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Luis Henriques <luis.henriques@canonical.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Jiri Slaby <jslaby@suse.cz>,
        stable@vger.kernel.org, linux-kernel@vger.kernel.org,
        Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover
 whole kernel range
Message-ID: <20160106133155.GD2671@codeblueprint.co.uk>
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On Wed, 06 Jan, at 11:24:55AM, Luis Henriques wrote:
> On Wed, Jan 06, 2016 at 11:00:31AM +0000, Matt Fleming wrote:
> > On Wed, 06 Jan, at 11:47:20AM, Paolo Bonzini wrote:
> > > 
> > > Without testing the problematic scenario explicitly (32-bit UEFI
> > > kernel), I think this patch and 26/91 should not be backported to
> > > kernels that do not have 23a0d4e8fa6d.
> > 
> > I tend to agree.
> 
> I can see these 2 commits in kernels as old as 3.10 (which definitely do
> not include 23a0d4e8fa6d).  Does this mean these should be reverted from
> stable kernels that already include these patches?  Or would you rather
> recommend to backport 23a0d4e8fa6d?

That depends on your appetite for risk ;-)

23a0d4e8fa6d does fix a legitimate bug, albeit one that no one seems
to have ever hit. Personally, I'd go for backporting 23a0d4e8fa6d.