@@ -100,3 +100,35 @@ func doesSupportNativeDiff(d string) error {

 	return nil

 }

+

+// supportsMultipleLowerDir checks if the system supports multiple lowerdirs,

+// which is required for the overlay2 driver. On 4.x kernels, multiple lowerdirs

+// are always available (so this check isn't needed), and backported to RHEL and

+// CentOS 3.x kernels (3.10.0-693.el7.x86_64 and up). This function is to detect

+// support on those kernels, without doing a kernel version compare.

+func supportsMultipleLowerDir(d string) error {

+	td, err := ioutil.TempDir(d, "multiple-lowerdir-check")

+	if err != nil {

+		return err

+	}

+	defer func() {

+		if err := os.RemoveAll(td); err != nil {

+			logrus.Warnf("Failed to remove check directory %v: %v", td, err)

+		}

+	}()

+

+	for _, dir := range []string{"lower1", "lower2", "upper", "work", "merged"} {

+		if err := os.Mkdir(filepath.Join(td, dir), 0755); err != nil {

+			return err

+		}

+	}

+

+	opts := fmt.Sprintf("lowerdir=%s:%s,upperdir=%s,workdir=%s", path.Join(td, "lower2"), path.Join(td, "lower1"), path.Join(td, "upper"), path.Join(td, "work"))

+	if err := unix.Mount("overlay", filepath.Join(td, "merged"), "overlay", 0, opts); err != nil {

+		return errors.Wrap(err, "failed to mount overlay")

+	}

+	if err := unix.Unmount(filepath.Join(td, "merged"), 0); err != nil {

+		logrus.Warnf("Failed to unmount check directory %v: %v", filepath.Join(td, "merged"), err)

+	}

+	return nil

+}

@@ -16,8 +16,6 @@ import (

 	"strings"

 	"sync"

-	"github.com/sirupsen/logrus"

-

 	"github.com/docker/docker/daemon/graphdriver"

 	"github.com/docker/docker/daemon/graphdriver/overlayutils"

 	"github.com/docker/docker/daemon/graphdriver/quota"

@@ -32,9 +30,9 @@ import (

 	"github.com/docker/docker/pkg/parsers"

 	"github.com/docker/docker/pkg/parsers/kernel"

 	"github.com/docker/docker/pkg/system"

-	units "github.com/docker/go-units"

-

+	"github.com/docker/go-units"

 	"github.com/opencontainers/selinux/go-selinux/label"

+	"github.com/sirupsen/logrus"

 	"golang.org/x/sys/unix"

 )

@@ -137,12 +135,6 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 	if err != nil {

 		return nil, err

 	}

-	if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 0, Minor: 0}) < 0 {

-		if !opts.overrideKernelCheck {

-			return nil, graphdriver.ErrNotSupported

-		}

-		logrus.Warn("Using pre-4.0.0 kernel for overlay2, mount failures may require kernel update")

-	}

 	fsMagic, err := graphdriver.GetFSMagic(home)

 	if err != nil {

@@ -169,6 +161,17 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap

 		}

 	}

+	if kernel.CompareKernelVersion(*v, kernel.VersionInfo{Kernel: 4, Major: 0, Minor: 0}) < 0 {

+		if opts.overrideKernelCheck {

+			logrus.Warn("Using pre-4.0.0 kernel for overlay2, mount failures may require kernel update")

+		} else {

+			if err := supportsMultipleLowerDir(filepath.Dir(home)); err != nil {

+				logrus.Debugf("Multiple lower dirs not supported: %v", err)

+				return nil, graphdriver.ErrNotSupported

+			}

+		}

+	}

+

 	rootUID, rootGID, err := idtools.GetRootUIDGID(uidMaps, gidMaps)

 	if err != nil {

 		return nil, err