From: Zefan Li <lizefan@huawei.com>
To: Aditya Kali <adityakali@google.com>
Cc: <tj@kernel.org>, <serge.hallyn@ubuntu.com>, <luto@amacapital.net>,
<ebiederm@xmission.com>, <cgroups@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-api@vger.kernel.org>,
<mingo@redhat.com>, <containers@lists.linux-foundation.org>,
<jnagal@google.com>, <vgoyal@redhat.com>,
<richard.weinberger@gmail.com>
Subject: Re: [PATCHv3 8/8] cgroup: Add documentation for cgroup namespaces
Date: Fri, 12 Dec 2014 16:54:26 +0800 [thread overview]
Message-ID: <548AAD42.5010002@huawei.com> (raw)
In-Reply-To: <1417744550-6461-9-git-send-email-adityakali@google.com>
> +In its current form, the cgroup namespaces patcheset provides following
> +behavior:
> +
> +(1) The 'cgroupns-root' for a cgroup namespace is the cgroup in which
> + the process calling unshare is running.
> + For ex. if a process in /batchjobs/container_id1 cgroup calls unshare,
> + cgroup /batchjobs/container_id1 becomes the cgroupns-root.
> + For the init_cgroup_ns, this is the real root ('/') cgroup
> + (identified in code as cgrp_dfl_root.cgrp).
> +
> +(2) The cgroupns-root cgroup does not change even if the namespace
> + creator process later moves to a different cgroup.
> + $ ~/unshare -c # unshare cgroupns in some cgroup
> + [ns]$ cat /proc/self/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/
> + [ns]$ mkdir sub_cgrp_1
> + [ns]$ echo 0 > sub_cgrp_1/cgroup.procs
> + [ns]$ cat /proc/self/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/sub_cgrp_1
> +
> +(3) Each process gets its CGROUPNS specific view of /proc/<pid>/cgroup
> +(a) Processes running inside the cgroup namespace will be able to see
> + cgroup paths (in /proc/self/cgroup) only inside their root cgroup
> + [ns]$ sleep 100000 & # From within unshared cgroupns
> + [1] 7353
> + [ns]$ echo 7353 > sub_cgrp_1/cgroup.procs
> + [ns]$ cat /proc/7353/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/sub_cgrp_1
> +
> +(b) From global cgroupns, the real cgroup path will be visible:
> + $ cat /proc/7353/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/container_id1/sub_cgrp_1
> +
> +(c) From a sibling cgroupns (cgroupns root-ed at a different cgroup), cgroup
> + path relative to its own cgroupns-root will be shown:
> + # ns2's cgroupns-root is at '/batchjobs/container_id2'
> + [ns2]$ cat /proc/7353/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/../container_id2/sub_cgrp_1
Should be ../container_id1/sub_cgrp_1 ?
> +
> + Note that the relative path always starts with '/' to indicate that its
> + relative to the cgroupns-root of the caller.
If a path doesn't start with '/', then it's a relative path, so why make it start with '/'?
> +
> +(4) Processes inside a cgroupns can move in-and-out of the cgroupns-root
> + (if they have proper access to external cgroups).
> + # From inside cgroupns (with cgroupns-root at /batchjobs/container_id1), and
> + # assuming that the global hierarchy is still accessible inside cgroupns:
> + $ cat /proc/7353/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/sub_cgrp_1
> + $ echo 7353 > batchjobs/container_id2/cgroup.procs
> + $ cat /proc/7353/cgroup
> + 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/../container_id2
> +
> + Note that this kind of setup is not encouraged. A task inside cgroupns
> + should only be exposed to its own cgroupns hierarchy. Otherwise it makes
> + the virtualization of /proc/<pid>/cgroup less useful.
> +
> +(5) Setns to another cgroup namespace is allowed when:
> + (a) the process has CAP_SYS_ADMIN in its current userns
> + (b) the process has CAP_SYS_ADMIN in the target cgroupns' userns
> + No implicit cgroup changes happen with attaching to another cgroupns. It
> + is expected that the somone moves the attaching process under the target
> + cgroupns-root.
> +
s/the somone/someone
> +(6) When some thread from a multi-threaded process unshares its
> + cgroup-namespace, the new cgroupns gets applied to the entire
> + process (all the threads). This should be OK since
> + unified-hierarchy only allows process-level containerization. So
> + all the threads in the process will have the same cgroup.
> +
> +(7) The cgroup namespace is alive as long as there is atleast 1
s/atelast/at least
> + process inside it. When the last process exits, the cgroup
> + namespace is destroyed. The cgroupns-root and the actual cgroups
> + remain though.
> +
> +(8) Namespace specific cgroup hierarchy can be mounted by a process running
> + inside cgroupns:
> + $ mount -t cgroup -o __DEVEL__sane_behavior cgroup $MOUNT_POINT
> +
> + This will mount the unified cgroup hierarchy with cgroupns-root as the
> + filesystem root. The process needs CAP_SYS_ADMIN in its userns and mntns.
> +
>
next prev parent reply other threads:[~2014-12-12 8:55 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <adityakali-cgroupns>
2014-07-17 19:52 ` [PATCH 0/5] RFC: CGroup Namespaces Aditya Kali
2014-07-17 19:52 ` [PATCH 1/5] kernfs: Add API to get generate relative kernfs path Aditya Kali
2014-07-24 15:10 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 2/5] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-07-24 17:01 ` Serge Hallyn
2014-07-31 19:48 ` Aditya Kali
2014-08-04 23:12 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 3/5] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-07-24 16:59 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 4/5] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-07-24 17:03 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 5/5] cgroup: introduce cgroup namespaces Aditya Kali
2014-07-17 19:57 ` Andy Lutomirski
2014-07-17 20:55 ` Aditya Kali
2014-07-18 16:51 ` Andy Lutomirski
2014-07-18 18:51 ` Aditya Kali
2014-07-18 18:57 ` Andy Lutomirski
2014-07-21 22:11 ` Aditya Kali
2014-07-21 22:16 ` Andy Lutomirski
2014-07-23 19:52 ` Aditya Kali
2014-07-18 16:00 ` [PATCH 0/5] RFC: CGroup Namespaces Serge Hallyn
2014-07-24 16:10 ` Serge Hallyn
2014-07-24 16:36 ` Serge Hallyn
2014-07-25 19:29 ` Aditya Kali
2014-07-25 20:27 ` Andy Lutomirski
2014-07-29 4:51 ` Serge E. Hallyn
2014-07-29 15:08 ` Andy Lutomirski
2014-07-29 16:06 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 0/8] " Aditya Kali
2014-10-13 21:23 ` [PATCHv1 1/8] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-10-16 16:07 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-10-16 16:08 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 3/8] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-10-16 16:13 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 4/8] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-10-16 16:14 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 5/8] cgroup: introduce cgroup namespaces Aditya Kali
2014-10-16 16:37 ` Serge E. Hallyn
2014-10-24 1:03 ` Aditya Kali
2014-10-25 3:16 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 6/8] cgroup: restrict cgroup operations within task's cgroupns Aditya Kali
2014-10-17 9:28 ` Serge E. Hallyn
2014-10-22 19:06 ` Aditya Kali
2014-10-19 4:57 ` Eric W. Biederman
2014-10-13 21:23 ` [PATCHv1 7/8] cgroup: cgroup namespace setns support Aditya Kali
2014-10-16 21:12 ` Serge E. Hallyn
2014-10-16 21:17 ` Andy Lutomirski
2014-10-16 21:22 ` Aditya Kali
2014-10-16 21:47 ` Serge E. Hallyn
2014-10-19 5:23 ` Eric W. Biederman
2014-10-19 18:26 ` Andy Lutomirski
2014-10-20 4:55 ` Eric W.Biederman
2014-10-21 0:20 ` Andy Lutomirski
2014-10-21 4:49 ` Eric W. Biederman
2014-10-21 5:03 ` Andy Lutomirski
2014-10-21 5:42 ` Eric W. Biederman
2014-10-21 5:49 ` Andy Lutomirski
2014-10-21 18:49 ` Aditya Kali
2014-10-21 19:02 ` Andy Lutomirski
2014-10-21 22:33 ` Aditya Kali
2014-10-21 22:42 ` Andy Lutomirski
2014-10-22 0:46 ` Aditya Kali
2014-10-22 0:58 ` Andy Lutomirski
2014-10-22 18:37 ` Aditya Kali
2014-10-22 18:50 ` Andy Lutomirski
2014-10-22 19:42 ` Tejun Heo
2014-10-17 9:52 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 8/8] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-10-17 12:19 ` Serge E. Hallyn
2014-10-14 22:42 ` [PATCHv1 0/8] CGroup Namespaces Andy Lutomirski
2014-10-14 23:33 ` Aditya Kali
2014-10-19 4:54 ` Eric W. Biederman
2015-07-22 18:10 ` Vincent Batts
2014-10-31 19:18 ` [PATCHv2 0/7] " Aditya Kali
2014-10-31 19:18 ` [PATCHv2 1/7] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-10-31 19:18 ` [PATCHv2 2/7] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-10-31 19:18 ` [PATCHv2 3/7] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-10-31 19:18 ` [PATCHv2 4/7] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-10-31 19:18 ` [PATCHv2 5/7] cgroup: introduce cgroup namespaces Aditya Kali
2014-11-01 0:02 ` Andy Lutomirski
2014-11-01 0:58 ` Eric W. Biederman
2014-11-03 23:42 ` Aditya Kali
2014-11-03 23:40 ` Aditya Kali
2014-11-04 1:56 ` Aditya Kali
2014-10-31 19:19 ` [PATCHv2 6/7] cgroup: cgroup namespace setns support Aditya Kali
2014-10-31 19:19 ` [PATCHv2 7/7] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-11-01 0:07 ` Andy Lutomirski
2014-11-01 2:59 ` Eric W. Biederman
2014-11-01 3:29 ` Andy Lutomirski
2014-11-03 23:12 ` Aditya Kali
2014-11-03 23:15 ` Andy Lutomirski
2014-11-03 23:23 ` Aditya Kali
2014-11-03 23:48 ` Andy Lutomirski
2014-11-04 0:12 ` Aditya Kali
2014-11-04 0:17 ` Andy Lutomirski
2014-11-04 0:49 ` Aditya Kali
2014-11-04 13:57 ` Tejun Heo
2014-11-06 17:28 ` Aditya Kali
2014-11-01 1:09 ` Eric W. Biederman
2014-11-03 22:46 ` Aditya Kali
[not found] ` <CAGr1F2Hd_PS_AscBGMXdZC9qkHGRUp-MeQvJksDOQkRBB3RGoA@mail.gmail.com>
2014-11-03 22:56 ` Andy Lutomirski
2014-11-04 13:46 ` Tejun Heo
2014-11-04 15:00 ` Andy Lutomirski
2014-11-04 15:50 ` Serge E. Hallyn
2014-11-12 17:48 ` Aditya Kali
2014-11-04 1:59 ` Aditya Kali
2014-11-04 13:10 ` [PATCHv2 0/7] CGroup Namespaces Vivek Goyal
2014-11-06 17:33 ` Aditya Kali
2014-11-26 22:58 ` Richard Weinberger
2014-12-02 19:14 ` Aditya Kali
2014-12-05 1:55 ` [PATCHv3 0/8] " Aditya Kali
2014-12-05 1:55 ` [PATCHv3 1/8] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-12-05 1:55 ` [PATCHv3 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-12-05 1:55 ` [PATCHv3 3/8] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-12-05 1:55 ` [PATCHv3 4/8] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-12-05 1:55 ` [PATCHv3 5/8] cgroup: introduce cgroup namespaces Aditya Kali
2014-12-12 8:54 ` Zefan Li
2014-12-05 1:55 ` [PATCHv3 6/8] cgroup: cgroup namespace setns support Aditya Kali
2014-12-05 1:55 ` [PATCHv3 7/8] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-12-12 8:55 ` Zefan Li
2014-12-05 1:55 ` [PATCHv3 8/8] cgroup: Add documentation for cgroup namespaces Aditya Kali
2014-12-12 8:54 ` Zefan Li [this message]
2015-01-05 22:54 ` Aditya Kali
2014-12-14 23:05 ` Richard Weinberger
2015-01-05 22:48 ` Aditya Kali
2015-01-05 22:52 ` Richard Weinberger
2015-01-05 23:53 ` Eric W. Biederman
2015-01-06 0:07 ` Richard Weinberger
2015-01-06 0:10 ` Aditya Kali
2015-01-06 0:17 ` Richard Weinberger
2015-01-06 23:20 ` Aditya Kali
2015-01-06 23:39 ` Richard Weinberger
2015-01-07 9:28 ` Richard Weinberger
2015-01-07 14:45 ` Eric W. Biederman
2015-01-07 19:30 ` Serge E. Hallyn
2015-01-07 22:14 ` Eric W. Biederman
2015-01-07 22:45 ` Tejun Heo
2015-01-07 23:02 ` Eric W. Biederman
2015-01-07 23:06 ` Tejun Heo
2015-01-07 23:09 ` Eric W. Biederman
2015-01-07 23:16 ` Tejun Heo
2015-01-07 23:27 ` Eric W. Biederman
2015-01-07 23:35 ` Tejun Heo
2015-02-11 3:46 ` Serge E. Hallyn
2015-02-11 4:09 ` Tejun Heo
2015-02-11 4:29 ` Serge E. Hallyn
2015-02-11 5:02 ` Eric W. Biederman
2015-02-11 5:17 ` Tejun Heo
2015-02-11 6:29 ` Eric W. Biederman
2015-02-11 14:36 ` Tejun Heo
2015-02-11 16:00 ` Serge E. Hallyn
2015-02-11 16:03 ` Tejun Heo
2015-02-11 16:18 ` Serge E. Hallyn
2015-02-11 5:10 ` Tejun Heo
2015-01-07 18:57 ` Aditya Kali
2014-12-05 3:20 ` [PATCHv3 0/8] CGroup Namespaces Aditya Kali
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