cgroups.patch

diff --git a/pkg/cgroups/cgroups.go b/pkg/cgroups/cgroups.go
index b40e1a3..3df82c2 100644
--- a/pkg/cgroups/cgroups.go
+++ b/pkg/cgroups/cgroups.go
@@ -62,7 +62,15 @@ func GetInitCgroupDir(subsystem string) (string, error) {
 	return parseCgroupFile(subsystem, f)
 }
 
-func (c *Cgroup) Path(root, subsystem string) (string, error) {
+func (c *Cgroup) Path(subsystem string) (string, error) {
+	root, err := FindCgroupMountpoint(subsystem)
+	if err != nil {
+		return "", err
+	}
+	// We get to handle both "/sys/fs/cgroup" and "/sys/fs/cgroup/devices".
+	if !strings.HasSuffix(root, "/"+subsystem) {
+		root = filepath.Join(root, subsystem)
+	}
 	cgroup := c.Name
 	if c.Parent != "" {
 		cgroup = filepath.Join(c.Parent, cgroup)
@@ -71,11 +79,11 @@ func (c *Cgroup) Path(root, subsystem string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return filepath.Join(root, subsystem, initPath, cgroup), nil
+	return filepath.Join(root, initPath, cgroup), nil
 }
 
-func (c *Cgroup) Join(root, subsystem string, pid int) (string, error) {
-	path, err := c.Path(root, subsystem)
+func (c *Cgroup) Join(subsystem string, pid int) (string, error) {
+	path, err := c.Path(subsystem)
 	if err != nil {
 		return "", err
 	}
@@ -88,9 +96,9 @@ func (c *Cgroup) Join(root, subsystem string, pid int) (string, error) {
 	return path, nil
 }
 
-func (c *Cgroup) Cleanup(root string) error {
+func (c *Cgroup) Cleanup() error {
 	get := func(subsystem string) string {
-		path, _ := c.Path(root, subsystem)
+		path, _ := c.Path(subsystem)
 		return path
 	}
 
@@ -98,6 +106,7 @@ func (c *Cgroup) Cleanup(root string) error {
 		get("memory"),
 		get("devices"),
 		get("cpu"),
+		get("cpuset"),
 	} {
 		os.RemoveAll(path)
 	}
@@ -130,32 +139,34 @@ func (c *Cgroup) Apply(pid int) error {
 	// systemd and the dbus api, and one is based on raw cgroup fs operations
 	// following the pre-single-writer model docs at:
 	// http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups/
-	//
+
 	// we can pick any subsystem to find the root
 	cgroupRoot, err := FindCgroupMountpoint("cpu")
 	if err != nil {
 		return err
 	}
-	cgroupRoot = filepath.Dir(cgroupRoot)
-
 	if _, err := os.Stat(cgroupRoot); err != nil {
 		return fmt.Errorf("cgroups fs not found")
 	}
-	if err := c.setupDevices(cgroupRoot, pid); err != nil {
+
+	if err := c.setupDevices(pid); err != nil {
 		return err
 	}
-	if err := c.setupMemory(cgroupRoot, pid); err != nil {
+	if err := c.setupMemory(pid); err != nil {
 		return err
 	}
-	if err := c.setupCpu(cgroupRoot, pid); err != nil {
+	if err := c.setupCpu(pid); err != nil {
+		return err
+	}
+	if err := c.setupCpuSet(pid); err != nil {
 		return err
 	}
 	return nil
 }
 
-func (c *Cgroup) setupDevices(cgroupRoot string, pid int) (err error) {
+func (c *Cgroup) setupDevices(pid int) (err error) {
 	if !c.DeviceAccess {
-		dir, err := c.Join(cgroupRoot, "devices", pid)
+		dir, err := c.Join("devices", pid)
 		if err != nil {
 			return err
 		}
@@ -203,9 +214,9 @@ func (c *Cgroup) setupDevices(cgroupRoot string, pid int) (err error) {
 	return nil
 }
 
-func (c *Cgroup) setupMemory(cgroupRoot string, pid int) (err error) {
+func (c *Cgroup) setupMemory(pid int) (err error) {
 	if c.Memory != 0 || c.MemorySwap != 0 {
-		dir, err := c.Join(cgroupRoot, "memory", pid)
+		dir, err := c.Join("memory", pid)
 		if err != nil {
 			return err
 		}
@@ -234,10 +245,10 @@ func (c *Cgroup) setupMemory(cgroupRoot string, pid int) (err error) {
 	return nil
 }
 
-func (c *Cgroup) setupCpu(cgroupRoot string, pid int) (err error) {
+func (c *Cgroup) setupCpu(pid int) (err error) {
 	// We always want to join the cpu group, to allow fair cpu scheduling
 	// on a container basis
-	dir, err := c.Join(cgroupRoot, "cpu", pid)
+	dir, err := c.Join("cpu", pid)
 	if err != nil {
 		return err
 	}
@@ -248,3 +259,19 @@ func (c *Cgroup) setupCpu(cgroupRoot string, pid int) (err error) {
 	}
 	return nil
 }
+
+func (c *Cgroup) setupCpuSet(pid int) (err error) {
+	// Necessary in some edge cases, but doesn't hurt the general case.
+	dir, err := c.Join("cpuset", pid)
+	if err != nil {
+		return err
+	}
+	// TODO don't overwrite non-empty files here
+	if err := writeFile(dir, "cpuset.cpus", "0"); err != nil {
+		return err
+	}
+	if err := writeFile(dir, "cpuset.mems", "0"); err != nil {
+		return err
+	}
+	return nil
+}