From mboxrd@z Thu Jan  1 00:00:00 1970
From: Philipp Hahn <hahn@univention.de>
Subject: Re: xenstored crashes with SIGSEGV
Date: Tue, 16 Dec 2014 13:04:13 +0100
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>, Frediano Ziglio <freddy77@gmail.com>, Xen-devel@lists.xen.org
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Hello,

On 16.12.2014 11:45, Ian Campbell wrote:
> On Mon, 2014-12-15 at 23:29 +0100, Philipp Hahn wrote:
>>> I notice in your bugzilla (for a different occurrence, I think):
>>>> [2090451.721705] univention-conf[2512]: segfault at ff00000000 ip 000000000045e238 sp 00007ffff68dfa30 error 6 in python2.6[400000+21e000]
>>>
>>> Which appears to have faulted access 0xff000000000 too. It looks like
>>> this process is a python thing, it's nothing to do with xenstored I
>>> assume?
>>
>> Yes, that's one univention-config, which is completely independent of
>> xen(stored).
>>
>>> It seems rather coincidental that it should be accessing the 
>>> same sort of address and be faulting.
>>
>> Yes, good catch. I'll have another look at those core dumps.
> 
> With this in mind, please can you confirm what model of machines you've
> seen this on, and in particular whether they are all the same class of
> machine or whether they are significantly different.

They are all from the same vendor, but I have to check the individual
models and firmware versions, which might take some time.

> The reason being that randomly placed 0xff values in a field of 0x00
> could possibly indicate hardware (e.g. a GPU) DMAing over the wrong
> memory pages.

Good catch: that would explain why it only happens for us and no one
other has seen that strange bug before.

Thanks you again.
Philipp Hahn