[Devel] Re: [PATCH 0/13] Pid namespaces (OpenVZ view)

[Pavel Emelianov]

Serge E. Hallyn wrote:
> Quoting Eric W. Biederman (ebiederm at xmission.com):
>> "Serge E. Hallyn" <serue at us.ibm.com> writes:
>>
>>>> 3. Cleaner logic for namespace migration: with this approach
>>>>    one need to save the virtual pid and let global one change;
>>>>    with Suka's logic this is not clear how to migrate the level
>>>>    2 namespace (concerning init to be level 0).
>>> This is a very good point.
>>>
>>> How *would* we migrate the pids at the second level?
>> As long as you don't try and restore pids into the initial pid namespace
>> it isn't a problem.  You just record the pid hierarchy and the pid
>> for a task in that hierarchy.  There really is nothing special going on
>> that should make migration hard.
>>
>> Or did I miss something?
> 
> Hmm, no, i guess you are right.  I was thinking that getting the pid for
> a process woudl be done purely from userspace, but I guess along with a
> kernel helper to *set* pids, we could also have a kernel helper to get
> all pids for all pid namespaces "above" that of the process doing the
> checkpoint.

So do you agree that if we migrate a VS we need to migrate the whole VS?

> Makes sense.
> 
> thanks,
> -serge
>