Re: [Xen-devel] Re: [PATCH] [xen, xencomm] various xencomm fixes (was Re: [XenPPC] Re: [Xen-ia64-devel] [PATCH 1/2] remove xencomm page size limit(xen side))

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Fri, Aug 10, 2007 at 01:54:47PM -0500, Hollis Blanchard wrote:
> I don't see how we'd ever hit this case though, nor why we'd panic the
> domain. How could paddr_to_maddr() ever return an maddr that doesn't
> belong to the current domain? If paddr is invalid, an error should be
> returned from there and propagated up, which is better than killing the
> whole domain IMHO...

I agree with you that we should return an error instead of panicing domain.

After getting maddr, another vcpu of the domain can free the page
with the decrease reservation hypercall at the same time.
Please remember that Xen supports SMP and balloon.
Then when accessing the page of maddr, the page might be used 
for another purpose.
Such a domain behaviour doesn't make sense. Howerver nothing
prevents it.

-- 
yamahata

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