linux-kernel - Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range

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Message-ID: <20160108133648.GB4372@ares>
Date:	Fri, 8 Jan 2016 13:36:48 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	Paolo Bonzini <pbonzini@...hat.com>, Jiri Slaby <jslaby@...e.cz>,
	stable@...r.kernel.org, linux-kernel@...r.kernel.org,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Kamal Mostafa <kamal@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover
 whole kernel range

On Fri, Jan 08, 2016 at 11:56:34AM +0000, Matt Fleming wrote:
> 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.

Awesome, thanks!  I'll queue it for the next 3.16 release.

Cheers,
--
Luís