diff --git a/libcontainer/cgroups/fs/cpuset.go b/libcontainer/cgroups/fs/cpuset.go
index bfc900e3f..a0c3c5f68 100644
--- a/libcontainer/cgroups/fs/cpuset.go
+++ b/libcontainer/cgroups/fs/cpuset.go
@@ -62,7 +62,11 @@ func (s *CpusetGroup) ApplyDir(dir string, cgroup *configs.Cgroup, pid int) erro
 	if err != nil {
 		return err
 	}
-	root := filepath.Dir(cgroups.GetClosestMountpointAncestor(dir, string(mountInfo)))
+	root, err := cgroups.GetClosestMountpointAncestor(dir, string(mountInfo))
+	if err != nil {
+		return err
+	}
+	root = filepath.Dir(root)
 	// 'ensureParent' start with parent because we don't want to
 	// explicitly inherit from parent, it could conflict with
 	// 'cpuset.cpu_exclusive'.
diff --git a/libcontainer/cgroups/utils.go b/libcontainer/cgroups/utils.go
index 8cdd6b7ed..9859557a7 100644
--- a/libcontainer/cgroups/utils.go
+++ b/libcontainer/cgroups/utils.go
@@ -16,6 +16,7 @@ import (
 	"time"
 
 	units "github.com/docker/go-units"
+	"github.com/moby/sys/mountinfo"
 	"golang.org/x/sys/unix"
 )
 
@@ -126,19 +127,25 @@ func isSubsystemAvailable(subsystem string) bool {
 	return avail
 }
 
-func GetClosestMountpointAncestor(dir, mountinfo string) string {
-	deepestMountPoint := ""
-	for _, mountInfoEntry := range strings.Split(mountinfo, "\n") {
-		mountInfoParts := strings.Fields(mountInfoEntry)
-		if len(mountInfoParts) < 5 {
-			continue
-		}
-		mountPoint := mountInfoParts[4]
-		if strings.HasPrefix(mountPoint, deepestMountPoint) && strings.HasPrefix(dir, mountPoint) {
-			deepestMountPoint = mountPoint
+func GetClosestMountpointAncestor(dir, data string) (string, error) {
+	mi, err := mountinfo.GetMountsFromReader(strings.NewReader(data), mountinfo.ParentsFilter(dir))
+	if err != nil {
+		return "", err
+	}
+	if len(mi) < 1 {
+		return "", err
+	}
+
+	// find the longest mount point
+	var idx, maxlen int
+	for i := range mi {
+		if len(mi[i].Mountpoint) > maxlen {
+			maxlen = len(mi[i].Mountpoint)
+			idx = i
 		}
 	}
-	return deepestMountPoint
+
+	return mi[idx].Mountpoint, nil
 }
 
 func FindCgroupMountpointDir() (string, error) {
diff --git a/libcontainer/cgroups/utils_test.go b/libcontainer/cgroups/utils_test.go
index adf266858..a3be72443 100644
--- a/libcontainer/cgroups/utils_test.go
+++ b/libcontainer/cgroups/utils_test.go
@@ -374,7 +374,7 @@ func TestIgnoreCgroup2Mount(t *testing.T) {
 }
 
 func TestGetClosestMountpointAncestor(t *testing.T) {
-	fakeMountInfo := ` 18 24 0:17 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw
+	const fakeMountInfo = `18 24 0:17 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw
 100 99 1:31 / /foo/bar rw,relatime - fake fake rw,fake
 100 99 1:31 / /foo/bar/baz2 rw,relatime - fake fake rw,fake
 100 99 1:31 / /foo/bar/baz rw,relatime - fake fake rw,fake
@@ -382,8 +382,8 @@ func TestGetClosestMountpointAncestor(t *testing.T) {
 100 99 1:31 / /foo/bar/baz3 rw,relatime - fake fake rw,fake
 100 99 1:31 / /foo rw,relatime - fake fake rw,fake
 100 99 1:31 / /unrelated rw,relatime - fake fake rw,fake
-100 99 1:31 / / rw,relatime - fake fake rw,fake
-`
+100 99 1:31 / / rw,relatime - fake fake rw,fake`
+
 	testCases := []struct {
 		input  string
 		output string
@@ -395,7 +395,10 @@ func TestGetClosestMountpointAncestor(t *testing.T) {
 	}
 
 	for _, c := range testCases {
-		mountpoint := GetClosestMountpointAncestor(c.input, fakeMountInfo)
+		mountpoint, err := GetClosestMountpointAncestor(c.input, fakeMountInfo)
+		if err != nil {
+			t.Fatal(err)
+		}
 		if mountpoint != c.output {
 			t.Errorf("expected %s, got %s", c.output, mountpoint)
 		}