[CRIU] cgroups restore failure

[Andrei Vagin]

On Thu, Mar 15, 2018 at 04:59:17AM +0000, Radostin Stoyanov wrote:
> Hello,
> 
> I am facing the following problem on container restore:
> 
> (00.000311) cg: Preparing cgroups yard (cgroups restore mode 0x4)
> (00.000370) Error (criu/util.c:1150): Unable to mount tmpfs in
> .criu.cgyard.b7ASXZ: Invalid argument
> (00.000379) Error (criu/cgroup.c:1167): cg: Unable to umount
> .criu.cgyard.b7ASXZ: Invalid argument
> 
> The full restore.log output of criu is https://pastebin.com/jP75EewF
> The code that does the dump/restore is
> https://github.com/rst0git/libvirt/blob/live-migration/src/lxc/lxc_criu.c
> 
> Any ideas why the mount call fails with "Invalid argument"?

I don't have any ideas. You can add sleep(1000) after this error in criu
and try to understand what is going on there. You should be able to
enter a mount namespace of the criu process and call the mount command
to mount tmpfs in the directory what you see in the log.

If this doesn't help to understand the problem, then I start using the
heavy artillery. Usually  I add printk() in the kernel source or use
ftrace to investigate this sort of problems.

> 
> Thanks,
> Radostin
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