[PATCH 0/6][lxc][v3] Link LXC with USERCR

[Daniel Lezcano]

Serge E. Hallyn wrote:
> Quoting Daniel Lezcano (dlezcano at fr.ibm.com):
>> Sukadev Bhattiprolu wrote:
>>> lxc-checkpoint, lxc-restart in the LXC source tree are currently stubs.
>>> Following set of patches, when applied to LXC and built with USERCR as
>>> described below, enable enable lxc-checkpoint and lxc-restart of some
>>> simple containers
>> [ ... ]
>>
>>> 3. Checkpoint/restart a simple LXC container
>>>
>>> 	$ lxc-execute --name foo --rcfile lxc-no-netns.conf -- /bin/sleep 1000
>>>
>>> 	$ lxc-checkpoint --name foo --image /root/lxc-foo.ckpt
>>>
>>> 	$ lxc-stop --name foo
>>>
>>> 	$ lxc-restart --name foo --image /root/lxc-foo.ckpt
>> Finally, using ckpt-v20-dev, I succeeded to checkpoint sleep but
>> when I restart, I got the error:
>>
>> <4534>number of tasks: 2
>> <4534>number of vpids: 0
>> <4534>total tasks (including ghosts): 2
>> <4534>pid 2: inherit sid 0
>> <4534>pid 2: creator set to 1
>> <4534>====== TASKS
>> <4534>	[0] pid 1 ppid 0 sid 0 creator 0
>> <4534>	[1] pid 2 ppid 1 sid 0 creator 1
>> <4534>............
>> <4534>task[0].vidx = -1
>> <4534>task[1].vidx = -1
>> <4534>new pidns with init
>> <4534>forking child vpid 1 flags 0x321
>> <4534>task 1 forking with flags 20020011 numpids 1
>> <4534>task 1 pid[0]=0
>> <4535>====== PIDS ARRAY
>> <4535>[0] pid 1 ppid 0 sid 0 pgid 0
>> <4535>[1] pid 2 ppid 1 sid 0 pgid 0
>> <4535>............
>> Error: /dev/ptmx must be a link to /dev/pts/ptmx
>> <4534>forked child vpid 4536 (asked 1)
>> root task exited status 0
>>
>> What can I do to prevent this error ?
> 
> test -e /dev/pts/ptmx || (echo "Don't go through with the rest of this" && exit)
> rm -f /dev/ptmx
> ln -s /dev/pts/ptmx /dev/ptmx
> chmod 666 /dev/ptmx

I was able to CR a simple program like sleep.

But most of the simple test programs I run, exit right after the restart 
was marked successful instead of continuing their execution.

In the kernel I see the traces:

[26108:3:c/r:restore_debug_free:145] active pid was 3, ctx->errno 0
[26108:3:c/r:restore_debug_free:147] kflags 6 uflags 0 oflags 3
[26108:3:c/r:restore_debug_free:149] task[0] to run 1
[26108:3:c/r:restore_debug_free:149] task[1] to run 2
[26108:3:c/r:restore_debug_free:149] task[2] to run 3
[26108:3:c/r:restore_debug_free:174] pid 26104 type Coord state Success
[26108:3:c/r:restore_debug_free:174] pid 26106 type Root state Success
[26108:3:c/r:restore_debug_free:174] pid 26107 type Task state Success
[26108:3:c/r:restore_debug_free:174] pid 26108 type Task state Success
[26108:3:c/r:pgarr_release_pages:102] total pages 0
[26108:3:c/r:do_restart:1446] sys_restart returns -516

What does mean -516 ? an error ?

I am running on a x86_64.

Thanks
   -- Daniel