[CRIU] Error CRIU restore because pid not matched

[Pavel Emelyanov]

On 10/24/2014 08:08 PM, Aris Setyawan wrote:
>> This means, that pid 1813, with which the restored task wants to live,
>> is already busy.
> 
> Is this mean, that pid already used by another process?

Yes

>> This option was obsoleted some time ago, sorry. Now CRIU detects
>> and creates the namespaces itself.
> 
> I have read the code, and it will "always" raise error, if mismatch happened.

Exactly.

> How to prevent this?
> So it can't be fixed?

In theory we can let process live with whatever PID kernel allocates
for it, but our knowledge of glibc says that most likely there will
be BUGs.

One way to work around this is to unshare the pid namespace with
unshare -p, then call restore. But in this case you may suffer from
/proc being the proc from former pid namespace, not the new one. This,
in turn, can be solved by unsharing the mount namespace too and
re-mounting the /proc.

The most viable solution for this type of usecases is to checkpoint
and restore tasks living in namespaces from the very beginning, i.e.
start them in this or that form of container.


Thanks,
Pavel