Re: [Xen-devel] mem_sharing: summarized problems when domain is

To:	Jui-Hao Chiang <juihaochiang@xxxxxxxxx>
Subject:	Re: [Xen-devel] mem_sharing: summarized problems when domain is dying
From:	George Dunlap <dunlapg@xxxxxxxxx>
Date:	Fri, 21 Jan 2011 16:32:34 +0000
Cc:	MaoXiaoyun <tinnycloud@xxxxxxxxxxx>, xen devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxx>
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[sorry, accidentally sent too early]

On Fri, Jan 21, 2011 at 4:29 PM, George Dunlap <dunlapg@xxxxxxxxx> wrote:
> I'm not sure the exact rationale behind the "cannot fail" flag; but it
> looks like in grant_table.c, both callers of gfn_to_mfn_unshare()
> handle the case where the returned p2m entry is just

...invalid.  I wonder if "unsharing" the page, but marking the entry
invalid during death would help.

I suppose the problem there is that if you're keeping the VM around
but paused for analysis, you'll have holes in your address space.  But
just returning an invalid entry to the callers who try to unshare
pages might work.

 -George

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Re: [Xen-devel] mem_sharing: summarized problems when domain is dying