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

To: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Subject: Re: [Xen-devel] Question: dom0 electrocuted by implicitly unmapped grantrefs
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 24 Nov 2009 08:32:40 +0000
Cc: Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Question: dom0 electrocuted by implicitly unmapped grantrefs
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On 23/11/2009 23:07, "Daniel Stodden" <daniel.stodden@xxxxxxxxxx> wrote:

>> 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.
> Forgive my ignorance: Why can't it be released any more? To me it looks
> as if the mapping is already gone, so the entry is stale, and the caller
> just pointed at it somewhat asking for just that.

We can't usually reliably tell. In most cases the granting domain would
still be hanging around. It's just on that one unlikely path we happen to be
able to tell.

 -- Keir

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