Re: 2.6.29-rc7 pv_ops dom0 BUG / unable to handle kernel paging request

[Jeremy Fitzhardinge <jeremy@goop.org>]

Pasi Kärkkäinen wrote:
> On Wed, Mar 11, 2009 at 10:52:50PM +0200, Pasi Kärkkäinen wrote:
>   
>> On Sun, Mar 08, 2009 at 01:54:01PM +0200, Pasi Kärkkäinen wrote:
>>     
>>> On Sat, Mar 07, 2009 at 10:09:16PM -0800, Jeremy Fitzhardinge wrote:
>>>       
>>>> Pasi Kärkkäinen wrote:
>>>>         
>>>>> Hello!
>>>>>
>>>>> Latest git tree (updated some hours ago) boots up fine for me, xend can be 
>>>>> started etc, but some time after starting kernel compilation I get the 
>>>>> following BUG:
>>>>>
>>>>> http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-19-xen331-linux-2.6.29-rc7-bug.txt
>>>>>
>>>>> (XEN) mm.c:2006:d0 Bad type (saw 28000001 != exp e0000000) for mfn 436a3 
>>>>> (pfn 3d0a3)
>>>>> (XEN) mm.c:707:d0 Error getting mfn 436a3 (pfn 3d0a3) from L1 entry 
>>>>> 00000000436a3063 for dom0
>>>>> (XEN) mm.c:3640:d0 ptwr_emulate: could not get_page_from_l1e()
>>>>> BUG: unable to handle kernel paging request at c01cbd58
>>>>> IP: [<c0405d2f>] xen_set_pte+0x8c/0x96
>>>>>  
>>>>>           
>>>> Well, that's bad news.  It was trying to map a highmem pte page which 
>>>> didn't have the Pinned bit set on its page, but Xen thought it was a 
>>>> pinned pte page.  Not sure how it could get into that state, but its 
>>>> indicative of general memory corruption.
>>>>
>>>> What was going on at the time?  Was dom0 busy?  Were you running some domUs?
>>>>
>>>>         
>>> At that time I was compiling a kernel on dom0.. so dom0 was busy.
>>>
>>> No other domains running. 
>>>
>>>       
>> Same thing happened again.. with the latest tree (as of today).
>>
>> Again I was compiling a kernel in dom0, so dom0 was busy. No other domains
>> running. 
>>
>>     
>
> The exact same kernel booted on baremetal without Xen works OK, and doesn't
> BUG during kernel compilation. 
>
>   

That's good to know as a baseline, though the bug is Xen refusing to do 
a pte update, so I'd be surprised if it happened with Xen in the picture ;)

What happens if you disable CONFIG_HIGHPTE?

    J