[CRIU] [PATCH] zdtm: add a small program to create a zdtm container

[Christopher Covington]

On 08/12/2014 03:17 PM, Andrew Vagin wrote:
> On Tue, Aug 12, 2014 at 02:34:20PM -0400, Christopher Covington wrote:
>> Hi Andrey
>>
>> On 08/12/2014 12:13 PM, Andrey Vagin wrote:
>>> I didn't find a way how to do that with help "unshare".
>>> It's simpler to write this program. It looks better than tricks in
>>> zdtm.sh.
>>
>> How different is this from `criu restore -n mnt,pid,net,ipc`?
> 
> I don't understand the question. This program is used to execute zdtm.sh
> in a container to avoid races between tests.
> The most popular race condition is when one test takes PID of another
> test, and the second test can't be restored.

I guess I don't understand the -n, --namespace option to CRIU since I never
seemed to be able to get it to work. My intuition would be that it is supposed
to do the "interesting task" you describe below. Digging in to the matter, I
think I see why I've never gotten it to work:

commit ac845bd1d8f7298e97b779f587a1fb46dd5737a7
Author: Pavel Emelyanov <xemul at parallels.com>
Date:   Thu Jan 17 18:14:55 2013 +0400

    cr: Obsolete the --namespaces option

    It's no longer required to use this option -- two currently
    supported cases (tasks on host and tasks in containers) can
    be detected automatically. Keep this option for future.

> Maybe you mean that a test can be restored in a new pid namespace.
> Currently criu can't do that. Here is a few questions. Who will be
> the init process? The root task probably doesn't ready to be a sub-reaper.
> Do we need to remount /proc? If the answer is yes, we need to create
> a new mount namespace together with pidns.
> I think this is interesting task, which will be one day implemented.

Why not simply move the contents of test/zdtm_ct.c into crtools.c, executed
conditionally based on -n, --namespace, and call it initially implemented?

Christopher

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