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

[Kir Kolyshkin]

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.

--kir