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authorDaniel Lezcano <daniel.lezcano@free.fr>2010-10-27 15:33:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-27 18:03:09 -0700
commit97978e6d1f2da0073416870410459694fbdbfd9b (patch)
treee8ff2fe4119d03fa54a45e8a101adbf9fb91a385 /include
parent2d3cbf8bc852ac1bc3d098186143c5973f87b753 (diff)
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cgroup: add clone_children control file
The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/cgroup.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 709dfb901d1..ed4ba111bc8 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -154,6 +154,10 @@ enum {
* A thread in rmdir() is wating for this cgroup.
*/
CGRP_WAIT_ON_RMDIR,
+ /*
+ * Clone cgroup values when creating a new child cgroup
+ */
+ CGRP_CLONE_CHILDREN,
};
/* which pidlist file are we talking about? */