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From: John Rousseau <jrrousseau@gmail.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, kvm-devel <kvm@vger.kernel.org>
Subject: Re: KVM: MMU: avoid creation of unreachable pages in the shadow
Date: Tue, 25 Nov 2008 13:27:27 -0500	[thread overview]
Message-ID: <492C438F.70203@gmail.com> (raw)
In-Reply-To: <20081125143310.GA11578@dmt.cnet>

Marcelo Tosatti wrote:
> It is possible for a shadow page to have a parent link
> pointing to a freed page. When zapping a high level table,
> kvm_mmu_page_unlink_children fails to remove the parent_pte link.
> For that to happen, the child must be unreachable via the shadow 
> tree, which can happen in shadow_walk_entry if the guest pte was
> modified in between walk() and fetch(). Remove the parent pte 
> reference in such case.
> 
> Possible cause for oops in bug #2217430.

I'll apply this to the code that I'm testing, but with my change to 
2.6.27, kvm-79 and Avi's patch from bug #2217430, I haven't seen the 
problem again. I still have been testing with oos_shadow=0, which I'll 
get rid of now.

Thanks
-John



  reply	other threads:[~2008-11-25 18:27 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-25 14:33 KVM: MMU: avoid creation of unreachable pages in the shadow Marcelo Tosatti
2008-11-25 18:27 ` John Rousseau [this message]
2008-11-25 15:54   ` Marcelo Tosatti
2008-11-25 19:01     ` John Rousseau
2008-11-29  4:15     ` John Rousseau

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