backport of commit d274e95

client/lib/cgutil/cpuset_manager_v2.go

@@ -59,20 +59,20 @@ type cpusetManagerV2 struct {
 
 func NewCpusetManagerV2(parent string, reservable []uint16, logger hclog.Logger) CpusetManager {
 	if err := minimumRootControllers(); err != nil {
-		logger.Error("failed to enabled minimum set of cgroup controllers; disable cpuset management", "error", err)
+		logger.Error("failed to enabled minimum set of cgroup controllers; disabling cpuset management", "error", err)
 		return new(NoopCpusetManager)
 	}
 
 	parentAbs := filepath.Join(CgroupRoot, parent)
 	if err := os.MkdirAll(parentAbs, 0o755); err != nil {
-		logger.Error("failed to ensure nomad parent cgroup exists; disable cpuset management", "error", err)
+		logger.Error("failed to ensure nomad parent cgroup exists; disabling cpuset management", "error", err)
 		return new(NoopCpusetManager)
 	}
 
 	if len(reservable) == 0 {
 		// read from group
 		if cpus, err := GetCPUsFromCgroup(parent); err != nil {
-			logger.Error("failed to lookup cpus from parent cgroup; disable cpuset management", "error", err)
+			logger.Error("failed to lookup cpus from parent cgroup; disabling cpuset management", "error", err)
 			return new(NoopCpusetManager)
 		} else {
 			reservable = cpus
@@ -98,14 +98,21 @@ func minimumRootControllers() error {
 	if err != nil {
 		return err
 	}
+
 	required := set.From[string]([]string{"cpuset", "cpu", "io", "memory", "pids"})
 	enabled := set.From[string](strings.Fields(s))
 	needed := required.Difference(enabled)
+
+	if needed.Size() == 0 {
+		return nil // already sufficient
+	}
+
 	sb := new(strings.Builder)
 	for _, controller := range needed.List() {
 		sb.WriteString("+" + controller + " ")
 	}
-	activation := sb.String()
+
+	activation := strings.TrimSpace(sb.String())
 	return e.write("cgroup.subtree_control", activation)
 }