diff --git a/runsc/cgroup/cgroup.go b/runsc/cgroup/cgroup.go
index 0eb5821a9..df1fc03cb 100644
--- a/runsc/cgroup/cgroup.go
+++ b/runsc/cgroup/cgroup.go
@@ -57,7 +57,7 @@ var controllers = map[string]controller{
 	"devices":    &noop{},
 	"freezer":    &noop{},
 	"perf_event": &noop{},
-	"rdma":       &noop{isOptional: true},
+	"rdma":       &noop{},
 	"systemd":    &noop{},
 }
 
@@ -599,12 +599,10 @@ type controller interface {
 	skip(*specs.LinuxResources) error
 }
 
-type noop struct {
-	isOptional bool
-}
+type noop struct{}
 
 func (n *noop) optional() bool {
-	return n.isOptional
+	return true
 }
 
 func (*noop) set(*specs.LinuxResources, string) error {
@@ -612,9 +610,6 @@ func (*noop) set(*specs.LinuxResources, string) error {
 }
 
 func (n *noop) skip(*specs.LinuxResources) error {
-	if !n.isOptional {
-		panic("cgroup controller is not optional")
-	}
 	return nil
 }
 
@@ -808,8 +803,17 @@ func (*networkPrio) skip(spec *specs.LinuxResources) error {
 	return nil
 }
 
-type pids struct {
-	mandatory
+type pids struct{}
+
+func (*pids) optional() bool {
+	return true
+}
+
+func (*pids) skip(spec *specs.LinuxResources) error {
+	if spec != nil && spec.Pids != nil && spec.Pids.Limit > 0 {
+		return fmt.Errorf("Pids.Limit set but pids cgroup controller not found")
+	}
+	return nil
 }
 
 func (*pids) set(spec *specs.LinuxResources, path string) error {
diff --git a/runsc/cgroup/cgroup_test.go b/runsc/cgroup/cgroup_test.go
index 1447078a0..abd10756b 100644
--- a/runsc/cgroup/cgroup_test.go
+++ b/runsc/cgroup/cgroup_test.go
@@ -863,6 +863,12 @@ func TestOptional(t *testing.T) {
 		spec  *specs.LinuxResources
 		err   string
 	}{
+		{
+			name:  "pids",
+			ctrlr: &pids{},
+			spec:  &specs.LinuxResources{Pids: &specs.LinuxPids{Limit: 1}},
+			err:   "Pids.Limit set but pids cgroup controller not found",
+		},
 		{
 			name:  "net-cls",
 			ctrlr: &networkClass{},