linux-kernel - Re: [kvm-devel] guest crash on 2.6.20-rc4

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Message-ID: <45A40898.4040307@qumranet.com>
Date:	Tue, 09 Jan 2007 23:26:48 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Roland Dreier <rdreier@...co.com>
CC:	kvm-devel <kvm-devel@...ts.sourceforge.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [kvm-devel] guest crash on 2.6.20-rc4

Roland Dreier wrote:
> I'm running a 64-bit Fedora 6 install as a guest on a host running
> 2.6.20-rc4 with the kvm-10 userspace release.  The CPU is a Xeon 5160
> and I have 6 GB of RAM.  The guest is given 512 MB of memory.  I left
> the guest idle overnight, and the makewhatis cron job seems to have
> triggered this:
>
>     Unable to handle kernel paging request at ffff81000ba04000 RIP:
>      [<ffffffff8025f402>] clear_page+0x16/0x44
>   

I've managed to reproduce a bug with similar characteristics: a write 
fault into a present, writable kernel page.  The attached patch should 
fix it.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


View attachment "spurious-page-fault.patch" of type "text/x-patch" (387 bytes)