[Users] Mounting a cgroup namesapce (special device cgroup does not exist)

[Andrew Vagin]

On Sun, Mar 31, 2013 at 10:50:51AM +0300, David Shwatrz wrote:
> Hi,
> I appreciate if somebody who has Fedora 18 (or maybe other distro with
> support to cgroups) will try mounting namespaces (with mount -t cgroup
> -ons .....) and report upon success/failure. I believe this should
> work.

ns_cgroup has been removed a few years ago.
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=a77aea92010acf54ad785047234418d5d68772e2

commit a77aea92010acf54ad785047234418d5d68772e2
Author: Daniel Lezcano <daniel.lezcano at free.fr>
Date:   Thu May 26 16:25:23 2011 -0700

    cgroup: remove the ns_cgroup
    
    The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and
    leads to some problems:
    
      * cgroup creation is out-of-control
      * cgroup name can conflict when pids are looping
      * it is not possible to have a single process handling a lot of
        namespaces without falling in a exponential creation time
      * we may want to create a namespace without creating a cgroup
    
      The ns_cgroup was replaced by a compatibility flag 'clone_children',
      where a newly created cgroup will copy the parent cgroup values.
      The userspace has to manually create a cgroup and add a task to
      the 'tasks' file.


> 
> Best
> DavidS
> 
> 
> On Sun, Mar 31, 2013 at 10:18 AM, David Shwatrz <dshwatrz at gmail.com> wrote:
> > Hi,
> > This is Fedora 18:
> >
> > uname -r
> > 3.8.4-202.fc18.x86_64
> >
> > cat /proc/cgroups
> > #subsys_name hierarchy num_cgroups enabled
> > cpuset 2 1 1
> > cpu 3 37 1
> > cpuacct 3 37 1
> > memory 4 1 1
> > devices 5 1 1
> > freezer 6 1 1
> > net_cls 7 1 1
> > blkio 8 1 1
> > perf_event 9 1 1
> >
> > DS
> >
> > On Sun, Mar 31, 2013 at 7:55 AM, Corey Carpenter <fruitwerks at gmail.com> wrote:
> >> What is your host OS and Kernel version?
> >>
> >> Does /proc/cgroup exists, what are the contents?
> >>
> >> ... This would be a good start
> >>
> >> On Sat, Mar 30, 2013 at 10:51 PM, David Shwatrz <dshwatrz at gmail.com> wrote:
> >>>
> >>> Hello all,
> >>>
> >>> How should I mount a cgroup namesapce ?
> >>> Following this link I tried:
> >>>
> >>> mount -t cgroup -ons cgroup /cgroup
> >>>
> >>> But I got:
> >>> mount: special device cgroup does not exist
> >>>
> >>> I suppose some argument is missing.
> >>>
> >>> Can someone please guide me how to fix it?
> >>>
> >>> Regards,
> >>> DS
> >>> _______________________________________________
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> >>> Users at openvz.org
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> >>
> >>
> >>
> >>
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