[lxc-users] lxc progress and a few questions

[Tycho Andersen]

On Tue, Mar 29, 2016 at 11:17:26PM -0700, jjs - mainphrame wrote:
> Well, I've found some interesting things here today. I created a couple of
> privileged xenial containers, and sure enough, I was able to live migrate
> them back and forth between the 2 lxd hosts.
> 
> So far, so good.
> 
> Then I did an apt upgrade - among the changes was a kernel change from
>  4.4.0-15 to 4.4.0-16 - and live migration stopped working.
> 
> Here are the failure messages that resulted from attempting the very same
> live migrations that worked before the upgrade and reboot into 4.4.0-16:
> 
> root at raskolnikov:~# lxc move akira lxd2:
> error: Error transferring container data: checkpoint failed:
> (00.092234) Error (mount.c:740): mnt: 83:./sys/fs/cgroup/devices doesn't
> have a proper root mount
> (00.098187) Error (cr-dump.c:1600): Dumping FAILED.
> 
> 
> root at ronnie:~# lxc move third lxd:
> error: Error transferring container data: checkpoint failed:
> (00.076107) Error (mount.c:740): mnt: 326:./sys/fs/cgroup/perf_event
> doesn't have a proper root mount
> (00.080388) Error (cr-dump.c:1600): Dumping FAILED.

Yep, this is a known issue with -16. We need both a kernel patch and a
patch to CRIU before it will start working again. I have a branch at:

https://github.com/tych0/criu/tree/cgroup-root-mount

which should work if you want to keep playing with it, but hopefully
we'll have the situation sorted out in the next few days.

Tycho

> Jake
> 
> PS - Thanks for the html mail heads-up - I've been using google mail
> services for this domain. I'll have to look into the config options, and
> see if I can do the needful.

> 
> On Tue, Mar 29, 2016 at 12:45 PM, Andrey Repin <anrdaemon at yandex.ru> wrote:
> 
> > Greetings, jjs - mainphrame!
> >
> > >> On Mon, Mar 28, 2016 at 08:47:24PM -0700, jjs - mainphrame wrote:
> >  >>> I've looked at ct migration between 2 ubuntu 16.04 hosts today, and
> > had
> >  >>> some interesting problems;  I find that migration of stopped
> > containers
> >  >>> works fairly reliably; but live migration, well, it transfers a lot of
> >  >>> data, then exits with a failure message. I can then move the same
> >  >>> container, stopped, with no problem.
> >  >>>
> >  >>> The error is the same every time, a failure of "mkdtemp" -
> > >>
> > >>  It looks like your host /tmp isn't writable by the uid map that the
> > >>  container is being restored as?
> >
> >
> > > Which is odd, since /tmp has 1777 perms on both hosts, so I don't see how
> > > it could be a permissions problem. Surely the default apparmor profile is
> > > not the cause? You did give me a new idea though, and I'll set up a test
> > > with privileged containers for comparison. Is there a switch to enable
> > verbose logging?
> >
> > I've ran into the same issue once. Stumbled upon it for nearly a month,
> > falsely
> > blaming LXC.
> > Recreating a container's rootfs from scratch resolved the issue.
> > I know not of what caused it to begin with, must've been some kind of
> > glitch.
> >
> > P.S.
> > It would be great if you can configure your mail client to not use HTML
> > format
> > for lists.
> >
> >
> > --
> > With best regards,
> > Andrey Repin
> > Tuesday, March 29, 2016 22:43:04
> >
> > Sorry for my terrible english...
> > _______________________________________________
> > lxc-users mailing list
> > lxc-users at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-users
> >

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