[Xen-devel] Re: [PATCH] fix pgd_lock deadlock

To:	Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject:	[Xen-devel] Re: [PATCH] fix pgd_lock deadlock
From:	Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date:	Tue, 22 Feb 2011 09:08:54 -0800
Cc:	"Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Larry Woodman <lwoodman@xxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Hugh Dickins <hughd@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, Johannes Weiner <jweiner@xxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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On 02/22/2011 06:34 AM, Andrea Arcangeli wrote:
> 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.

Eh, very not keen about that.  I'd only consider it as a last resort.

In practice CONFIG_XEN is always enabled in distros, so the conditional
would always be done at runtime.

    J


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[Xen-devel] Re: [PATCH] fix pgd_lock deadlock