[lxc-users] LXC, criu and cgroups...

[Dirk Geschke]

Hi all,

I was just playing with lxd and tried the move command but it
failed with 

   error: checkpoint failed

I think, this is not a problem of lxd but of criu with cgroups.

The running container is semi-unprivileged, I can start it without
problems.

But if I use cgmanager, then criu fails with:

   Error (mount.c:624): 94:./sys/fs/cgroup/cgmanager doesn't have a proper root mount

If I do not use cgamager but mount /sys/fs/cgroup:

   mount -t cgroup cgroup /sys/fs/cgroup/

I get this error:

   Error (mount.c:624):
   74:./sys/fs/cgroup/cpuset,cpu,cpuacct,blkio,memory,devices,freezer,net_cls,perf_event,net_prio,hugetlb,debug/lxc/wheezy2 doesn't have a proper root mount

This is with criu 1.5.1, with version 1.3.1 I get the same errors,
but at least there are *.img files created (and deleted).

Has anyone an idea what is going wrong?

It is lxd-0.5, lxc-1.1.1 (the git repository says still 1.1.0?) and
kernel 4.0-rc6 with criu-1.5.1. The kernel is adjusted to work with
criu, except:

   # criu check
   Warn  (cr-check.c:581): Dirty tracking is OFF. Memory snapshot will not work.
   Looks good.

There is a kernel patch for this, but I did not find it. I don't
think, this causes the problem.

Has anyone an idea what is my mistake?

BTW: I started the container without lxd and tried lxc-checkpoint and
got the same errors. So I think it is not related to lxd but probably
to criu?

Best regards

Dirk

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