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Re: [Xen-devel] Re: xen crash in tmem: checking a xen pfn for domain own

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: xen crash in tmem: checking a xen pfn for domain ownership
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Mon, 20 Sep 2010 08:16:57 +0100
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>>> On 17.09.10 at 21:32, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
> Oh, depending on what you want to do with the page you may well want to
> get_page(current->domain, page). You don't hold a lock on the domain's p2m,
> so page ownerships can change under your feet, and hence getting a reference
> to the page, and checking the page's ownership at the same time, might be
> wise. And if you want to modify the page you should probably use
> get_page_and_type(..., PGT_writable_page).

That's particularly important for the pv case, where gfn_to_mfn() is
a no-op.


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