cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested...

[deliverable/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 79818507e444aa3050c9994841258292c294bd2e..b7d9606b17d75871ecb8f4a74390d89a044d10d8 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3954,8 +3954,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
 
        for_each_subsys(root, ss) {
-               struct cgroup_subsys_state *css = ss->create(cgrp);
+               struct cgroup_subsys_state *css;
 
+               css = ss->create(cgrp);
                if (IS_ERR(css)) {
                        err = PTR_ERR(css);
                        goto err_destroy;
@@ -3969,6 +3970,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                /* At error, ->destroy() callback has to free assigned ID. */
                if (clone_children(parent) && ss->post_clone)
                        ss->post_clone(cgrp);
+
+               if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
+                   parent->parent) {
+                       pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
+                                  current->comm, current->pid, ss->name);
+                       if (!strcmp(ss->name, "memory"))
+                               pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
+                       ss->warned_broken_hierarchy = true;
+               }
        }
 
        list_add(&cgrp->sibling, &cgrp->parent->children);