This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Question: dom0 electrocuted by implicitly unmapped grant

To: Daniel Stodden <daniel.stodden@xxxxxxxxxx>, Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Question: dom0 electrocuted by implicitly unmapped grantrefs
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 23 Nov 2009 22:52:31 +0000
Delivery-date: Mon, 23 Nov 2009 14:53:01 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1259016236.2758.277.camel@xxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcpsjoR8JXz0QDbmR8OsemNTwKhgtgAAR7Zc
Thread-topic: [Xen-devel] Question: dom0 electrocuted by implicitly unmapped grantrefs
User-agent: Microsoft-Entourage/
On 23/11/2009 22:43, "Daniel Stodden" <daniel.stodden@xxxxxxxxxx> wrote:

> I assume 'implicitly unmapped' therein refers to a case where rd is gone
> because ld in some or the other way already managed to tear down a
> mapping without an exlicit gnttab call? This correct? Otherwise killing
> ld would seem a bit rough to me :}

You are correct.

> Either way: is domain_crash(ld) the appropriate response? Why not just
> fail the op and let the caller live and learn?

It's arguable I suppose. An implicitly unmapped grant leaves a grant entry
which cannot be released until the mapping domain dies. It's a nasty kind of
leak, and I made the hypervisor's response to it suitably abrupt.

 -- Keir

Xen-devel mailing list