[CRIU] Pty-related Dump Failure

[Saied Kazemi]

Hi Cyrill,

As you know, we're trying to add checkpoint restore functionality to Docker
using CRIU.  The first step in the process is to add C/R to libcontainer
and test the result with the standalone nsinit utility that uses
libcontainer.

We need your help in resolving an issue related to pseudo terminals.  Below
is how you can reproduce the problem.  Attached is a tarball of nsinit and
CRIU image and log files (in checkpoint directory).  Please let me know if
you need instructions on how to build nsinit yourself.

Thanks in advance,

--Saied

[Terminal A]
$ mkdir busybox
$ curl -sSL '
https://github.com/jpetazzo/docker-busybox/raw/buildroot-2014.02/rootfs.tar'
| tar -xC busybox
(ignore mknod errors)
$ cd busybox
$ tty
/dev/pts/3
$ sudo nsinit exec --create sh
sh: can't access tty; job control turned off
/ # ls -l /proc/$$/fd
total 0
lrwx------    1 root     root            64 Mar 10 16:26 0 -> /dev/pts/3
lrwx------    1 root     root            64 Mar 10 16:26 1 -> /dev/pts/3
lrwx------    1 root     root            64 Mar 10 16:26 2 -> /dev/pts/3
/ # $

[Terminal B]
$ cd busybox
$ sudo nsinit -criu /path/to/criu checkpoint && echo OK
exit status 1:
$ sudo grep Error nsinit/checkpoint/dump.log
(00.138932) Error (tty.c:335): tty: Found slave peer index 3 without
correspond master peer
(00.139198) Error (cr-dump.c:1979): Dumping FAILED.
$
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