cgroups: strip LXC_AUTO_CGROUP_MIXED and LXC_AUTO_CGROUP_FULL_MIXED when cgroup…

src/lxc/cgroups/cgfsng.c

@@ -1910,8 +1910,19 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 			wants_force_mount = true;
 	}
 
-	if (cgns_supported() && container_uses_namespace(handler, CLONE_NEWCGROUP))
+	if (cgns_supported() && container_uses_namespace(handler, CLONE_NEWCGROUP)) {
 		in_cgroup_ns = true;
+		/*
+		 * When cgroup namespaces are supported and used by the
+		 * container the LXC_AUTO_CGROUP_MIXED and
+		 * LXC_AUTO_CGROUP_FULL_MIXED auto mount options don't apply
+		 * since the parent directory of the container's cgroup is not
+		 * accessible to the container.
+		 */
+		cg_flags &= ~LXC_AUTO_CGROUP_MIXED;
+		cg_flags &= ~LXC_AUTO_CGROUP_FULL_MIXED;
+	}
+
 	if (in_cgroup_ns && !wants_force_mount)
 		return true;