cgroup: notify ns_cgroup deprecated

The ns_cgroup will be removed very soon.  Let's warn, for this version,
ns_cgroup is deprecated.

Make ns_cgroup and clone_children exclusive.  If the clone_children is set
and the ns_cgroup is mounted, let's fail with EINVAL when the ns_cgroup
subsys is created (a printk will help the user to understand why the
creation fails).

Update the feature remove schedule file with the deprecated ns_cgroup.

Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c
index 2a5dfec8efe0..2c98ad94ba0e 100644
--- a/kernel/ns_cgroup.c
+++ b/kernel/ns_cgroup.c
@@ -85,6 +85,14 @@ static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
                 return ERR_PTR(-EPERM);
         if (!cgroup_is_descendant(cgroup, current))
                 return ERR_PTR(-EPERM);
+        if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
+                printk("ns_cgroup can't be created with parent "
+                       "'clone_children' set.\n");
+                return ERR_PTR(-EINVAL);
+        }
+
+        printk_once("ns_cgroup deprecated: consider using the "
+                    "'clone_children' flag without the ns_cgroup.\n");
 
         ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
         if (!ns_cgroup)