[CRIU] [PATCH] cgroup: support --cgroup-root on dump too

[Tycho Andersen]

Hi Kir,

On Mon, Sep 19, 2016 at 06:15:01PM -0700, Kir Kolyshkin wrote:
> On 09/13/2016 09:46 AM, Tycho Andersen wrote:
> >The problem here is again caused by systemd :). Every process lives in some
> >child cgroup and not the root one, so we end up with a bunch of stuff like:
> >
> >/init.scope
> >/system.slice/...
> >/user.slice/...
> >
> >and nothing in the root cgroup. However, systemd opens
> >/sys/fs/cgroup/systemd, changes the perms, and keeps a fd around.
> >Unfortuantely, we don't track the perms on the "real root" cgroup here,
> >because nothing is at that level, so when we restore, our cgroup perms
> >changing code doesn't catch this perms change, and we get:
> >
> >(00.361723)      1: Error (criu/files-reg.c:1487): File sys/fs/cgroup/systemd has bad mode 040755 (expect 040775)
> >
> >To fix this, let's just support the --cgroup-root argument on dump too, and
> >rewrite the cgroup paths we dump accordingly.
> 
> This calls for an update to Documentation/criu.txt, as well as criu --help
> output.
> Care to provide the patch?https://criu.org/CGroups might need some love,
> too.

I sent some patches and added a little blurb to the wiki, let me know
if that makes sense.

Thanks!

Tycho