[CRIU] criu_restore() in Open MPI problems

[Pavel Emelyanov]

On 04/09/2014 05:51 PM, Adrian Reber wrote:
> On Mon, Mar 24, 2014 at 03:07:11PM +0400, Andrew Vagin wrote:

Hi, Adrian!

>> I think the restore scheme should look like this:
>> We run orterun, which prepare pipes and executes "CRIU restore".
>> The OpenMPI plugin takes preparate pipes and restores them in a proper
>> file descriptors.
> 
> It took me a while, but now I tried to restore a process from
> orterun/mpirun with exec()ing 'criu restore' 

Thanks for doing this! :)

> I still get this error:
> 
> (00.030652)   4277: tty: open type pts id 0x2 index 14 (master 0 sid 0 pgrp 0 inherit 1)
> (00.030654)   4277: Error (tty.c:541): tty: Can't dup SELF_STDIN_OFF: Bad file descriptor
> (00.031052) Error (cr-restore.c:1035): 4277 exited, status=255
> (00.031072) Error (cr-restore.c:1577): Restoring FAILED.
> 
> You are talking about a plugin which restores the missing pipes. How
> would such a plugin have to look like? Do you have any examples on
> re-creating pipes in a plugin?

Well, we don't have the pipe-restoring plugins. But we have examples of
unknown file descriptors plugins at test/zdtm/live/static/criu-rtc.c. This
one sits on the cr_plugin_dump_file/cr_plugin_restore_file hooks. I think
it's perfectly possible to add needed for pipes.

You might also be interested in this mailing thread:
http://lists.openvz.org/pipermail/criu/2014-March/012929.html

In it Cyrill tried to provide hooks for intercepting dump of TCP sockets.
Intercepting of pipes dump should probably look similar.

BTW, since pipes we're talking about are really external (one end sits
outside of our dump tree) I think we should detect this fact and call
plugins for external pipes.

Hope that helps :) If you need more info -- feel free to ask.

Thanks,
Pavel