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Date: Fri, 8 Jan 2016 11:56:34 +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>,
        Kamal Mostafa <kamal@canonical.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover
 whole kernel range
Message-ID: <20160108115634.GG2532@codeblueprint.co.uk>
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On Wed, 06 Jan, at 02:22:37PM, Luis Henriques wrote:
> [ Adding Greg and Kamal ]
> 
> On Wed, Jan 06, 2016 at 01:31:55PM +0000, Matt Fleming wrote:
> > 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 ;-)
> >
> 
> Heh, I guess stable kernels aren't really about 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.
> 
> This commit doesn't seem to be too bad to backport.  I'm attaching 2
> backports:
> 
>  - one is for the 3.16 stable kernel,
>  - the other can be applied to 3.10, 3.12 and 3.13
> 
> (For the other kernels, I believe 23a0d4e8fa6d will be a clean
> cherry-pick.)

FWIW they look OK to me.