From: Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] fix pgd_lock deadlock
Date: Tue, 22 Feb 2011 15:34:21 +0100
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To: Jan Beulich <JBeulich@novell.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>, Andi Kleen <andi@firstfloor.org>, Hugh Dickins <hughd@google.com>, Jeremy Fitzhardinge <jeremy@goop.org>, the arch/x86 maintainers <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Andrew Morton <akpm@linux-foundation.org>, "Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Johannes Weiner <jweiner@redhat.com>, Larry Woodman <lwoodman@redhat.com>, Rik van Riel <riel@redhat.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
List-Id: xen-devel@lists.xenproject.org

On Tue, Feb 22, 2011 at 02:22:53PM +0000, Jan Beulich wrote:
> If everyone's okay with putting a couple of "if (xen_pv_domain())"
> into mm/fault.c - sure. I would have thought that this wouldn't be
> liked, hence the suggestion to make this depend on seeing the
> backlink be non-NULL.

I prefer the if (xen_pv_domain) so it also gets optimized away
at build time when CONFIG_XEN=n. I think it's also more self
explanatory to read.