[Lxc-users] Problem with core dumps generated from containers, apport

[Stéphane Graber]

On 04/25/2013 02:18 PM, Hans Feldt wrote:
> Thanks great! But what I don't (yet) understand is shouldn't the new %P
> behaviour be the default of %p instead?
> 
> I mean a container PID never makes sense in host user space since there
> is a 1:n mapping. Meaning PID x can have n mappings on the host.
> 
> Thanks,
> Hans

Well, to make apport work we actually need both as we need %P to figure
out what container that's and we need %p to tell apport in that
container what PID to look at.

So I preferred not to break things by changing the meaning of %p in the
kernel.

> On 04/25/2013 12:23 PM, Stéphane Graber wrote:
>> On 04/24/2013 02:10 PM, Hans Feldt wrote:
>>>> -----Original Message-----
>>>> From: Serge Hallyn [mailto:serge.hallyn at ubuntu.com]
>>>> Sent: den 23 april 2013 14:52
>>>> To: Hans Feldt
>>>> Cc: lxc-users at lists.sourceforge.net
>>>> Subject: Re: [Lxc-users] Problem with core dumps generated from
>>>> containers, apport
>>>
>>>>> 260 is the PID of my test program (sleep 1000) in the container. It of
>>>>> course had another PID on the host...
>>>>
>>>> Hm, well that's certainly surprising to me, but there it is, in
>>>> fs/coredump.c:format_corename(): case 'p' uses task_tgid_vnr().
>>>>
>>>> Would you like to send a patch upstream to add 'P' as an option for
>>>> using the
>>>> global pid?
>>>
>>> Sorry this is out of my competence. I did check the code you pointed
>>> at and I think there's
>>> a name space conversion thing missing before handing over the PID
>>> over to user space. I
>>> could not find what function could do the trick.
>>>
>>> As a workaround if I temporarily change the core_pattern to write to
>>> file instead, I
>>> should get a readable useable core dump from a container process
>>>
>>> Thanks,
>>> Hans
>>
>> I've proposed a patch against the upstream kernel which adds a new "%P"
>> with the global PID.
>>
>> This then makes the following core_pattern work on Ubuntu systems:
>> |/usr/sbin/chroot /proc/%P/root /usr/share/apport/apport %p %s %c
>>
>>
>> https://lkml.org/lkml/2013/4/24/518
>>
>>
> 


-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com

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