1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 8cda3bc3ae22..4bfb2908ec15 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -3183,6 +3183,16 @@ static int cgroup_enable_threaded(struct cgroup *cgrp)
         if (cgroup_is_threaded(cgrp))
                 return 0;
 
+        /*
+         * If @cgroup is populated or has domain controllers enabled, it
+         * can't be switched.  While the below cgroup_can_be_thread_root()
+         * test can catch the same conditions, that's only when @parent is
+         * not mixable, so let's check it explicitly.
+         */
+        if (cgroup_is_populated(cgrp) ||
+            cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
+                return -EOPNOTSUPP;
+
         /* we're joining the parent's domain, ensure its validity */
         if (!cgroup_is_valid_domain(dom_cgrp) ||
             !cgroup_can_be_thread_root(dom_cgrp))