[CRIU] Restore CRIU image across a host

[Tycho Andersen]

On Tue, Aug 04, 2015 at 05:40:48PM -0400, Hui Kang wrote:
> Hi, Tycho
> Thanks for your suggestion. I am using criu RPC calls, where I can not find
> the four mode for cgroup-manager. Instead, it is a bool type value.
> 
> optional bool			manage_cgroups	= 24;
> 
> Should I update my criu version (I am using v1.6)?

Oh, that's probably because the RPC struct wasn't updated to match the
new CLI options. It looks like in the current tree it is also a bool,
so updating to master won't help you. I'm sure a patch would be
welcome, though :)

Tycho

> - Hui
> 
> On Tue, Aug 4, 2015 at 5:15 PM, Tycho Andersen <tycho.andersen at canonical.com
> > wrote:
> 
> > On Tue, Aug 04, 2015 at 05:01:14PM -0400, Hui Kang wrote:
> > > Hi,
> > > I am trying to restore the process on a different criu host by
> > transferring
> > > the CRIU images. The checkpointed criu images are scp-ed to a different
> > > host; however the restore fails. The restore.log shows that
> > >
> > > (00.075765)      1: nr_restored_pages: 66
> > > (00.075772)      1: nr_shared_pages:   0
> > > (00.075779)      1: nr_droped_pages:   0
> > > (00.075829)      1: Found fd 1 (id pipe:[13922]) in inherit fd list
> > (caller
> > > close_old_fds)
> > > (00.075841)      1: Found fd 2 (id pipe:[13923]) in inherit fd list
> > (caller
> > > close_old_fds)
> > > (00.075859)      1: cg: Move into 2
> > >  1: cg:   `-> blkio//[PID]/tasks
> > > (00.075906)      1: cg:   `-> cpu//[PID]/tasks
> > > (00.075946)      1: cg:   `-> cpuacct//[PID]/tasks
> > > (00.075967)      1: cg:   `-> cpuset//[PID]/tasks
> > > (00.076008)      1: Error (cgroup.c:901): cg: Can't move into
> > > cpuset//[PID]/tasks (-1/0): No space left on device
> > > (00.082249) Error (cr-restore.c:1919): Restoring FAILED.
> > >
> > > Note that the process being migrated has its cgroup directory in the
> > source
> > > node, which apparently does not exist in the destination host. So I first
> > > mkdir /sys/fs/cgroup/cpu/PID .... and copy the content from the source to
> > > destination.
> >
> > You might want to use one of the new `--manage-cgroups full` mode to
> > do this for you. That said, moving something into cpuset's tasks fails
> > with ENOSPC for the following reasons (from cpuset(7)):
> >
> >        ENOSPC Attempted to write(2) the process ID (PID) of  a  process
> > to  a  cpuset
> >               tasks file when the cpuset had an empty cpuset.cpus or empty
> > cpuset.mems
> >               setting.
> >
> >        ENOSPC Attempted to write(2) an empty cpuset.cpus or cpuset.mems
> > setting  to  a
> >               cpuset that has tasks attached.
> >
> > So depending on what you copied over, it can cause some problems. In
> > `--manage-cgroups full` mode, criu's code should be smart enough to handle
> > things, though.
> >
> > Tycho
> >
> > > Is there anything wrong in these steps? Thanks.
> > >
> > > - Hui
> >
> > > _______________________________________________
> > > CRIU mailing list
> > > CRIU at openvz.org
> > > https://lists.openvz.org/mailman/listinfo/criu
> >
> >