Update godeps

vendor/github.com/opencontainers/runc/libcontainer/cgroups/cgroups.go

@@ -9,7 +9,7 @@ import (
 )
 
 type Manager interface {
-	// Apply cgroup configuration to the process with the specified pid
+	// Applies cgroup configuration to the process with the specified pid
 	Apply(pid int) error
 
 	// Returns the PIDs inside the cgroup set

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/apply_raw.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
 )
 
 var (
@@ -30,6 +31,7 @@ var (
 		&NetPrioGroup{},
 		&PerfEventGroup{},
 		&FreezerGroup{},
+		&NameGroup{GroupName: "name=systemd", Join: true},
 	}
 	CgroupProcesses  = "cgroup.procs"
 	HugePageSizes, _ = cgroups.GetHugePageSize()
@@ -94,11 +96,10 @@ func getCgroupRoot() (string, error) {
 }
 
 type cgroupData struct {
-	root   string
-	parent string
-	name   string
-	config *configs.Cgroup
-	pid    int
+	root      string
+	innerPath string
+	config    *configs.Cgroup
+	pid       int
 }
 
 func (m *Manager) Apply(pid int) (err error) {
@@ -129,12 +130,9 @@ func (m *Manager) Apply(pid int) (err error) {
 		return cgroups.EnterPid(m.Paths, pid)
 	}
 
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	paths := make(map[string]string)
-	defer func() {
-		if err != nil {
-			cgroups.RemovePaths(paths)
-		}
-	}()
 	for _, sys := range subsystems {
 		if err := sys.Apply(d); err != nil {
 			return err
@@ -144,7 +142,9 @@ func (m *Manager) Apply(pid int) (err error) {
 		// created then join consists of writing the process pids to cgroup.procs
 		p, err := d.path(sys.Name())
 		if err != nil {
-			if cgroups.IsNotFound(err) {
+			// The non-presence of the devices subsystem is
+			// considered fatal for security reasons.
+			if cgroups.IsNotFound(err) && sys.Name() != "devices" {
 				continue
 			}
 			return err
@@ -267,45 +267,31 @@ func getCgroupPath(c *configs.Cgroup) (string, error) {
 	return d.path("devices")
 }
 
-// pathClean makes a path safe for use with filepath.Join. This is done by not
-// only cleaning the path, but also (if the path is relative) adding a leading
-// '/' and cleaning it (then removing the leading '/'). This ensures that a
-// path resulting from prepending another path will always resolve to lexically
-// be a subdirectory of the prefixed path. This is all done lexically, so paths
-// that include symlinks won't be safe as a result of using pathClean.
-func pathClean(path string) string {
-	// Ensure that all paths are cleaned (especially problematic ones like
-	// "/../../../../../" which can cause lots of issues).
-	path = filepath.Clean(path)
-
-	// If the path isn't absolute, we need to do more processing to fix paths
-	// such as "../../../../<etc>/some/path". We also shouldn't convert absolute
-	// paths to relative ones.
-	if !filepath.IsAbs(path) {
-		path = filepath.Clean(string(os.PathSeparator) + path)
-		// This can't fail, as (by definition) all paths are relative to root.
-		path, _ = filepath.Rel(string(os.PathSeparator), path)
-	}
-
-	// Clean the path again for good measure.
-	return filepath.Clean(path)
-}
-
 func getCgroupData(c *configs.Cgroup, pid int) (*cgroupData, error) {
 	root, err := getCgroupRoot()
 	if err != nil {
 		return nil, err
 	}
 
-	// Clean the parent slice path.
-	c.Parent = pathClean(c.Parent)
+	if (c.Name != "" || c.Parent != "") && c.Path != "" {
+		return nil, fmt.Errorf("cgroup: either Path or Name and Parent should be used")
+	}
+
+	// XXX: Do not remove this code. Path safety is important! -- cyphar
+	cgPath := libcontainerUtils.CleanPath(c.Path)
+	cgParent := libcontainerUtils.CleanPath(c.Parent)
+	cgName := libcontainerUtils.CleanPath(c.Name)
+
+	innerPath := cgPath
+	if innerPath == "" {
+		innerPath = filepath.Join(cgParent, cgName)
+	}
 
 	return &cgroupData{
-		root:   root,
-		parent: c.Parent,
-		name:   c.Name,
-		config: c,
-		pid:    pid,
+		root:      root,
+		innerPath: innerPath,
+		config:    c,
+		pid:       pid,
 	}, nil
 }
 
@@ -333,11 +319,10 @@ func (raw *cgroupData) path(subsystem string) (string, error) {
 		return "", err
 	}
 
-	cgPath := filepath.Join(raw.parent, raw.name)
 	// If the cgroup name/path is absolute do not look relative to the cgroup of the init process.
-	if filepath.IsAbs(cgPath) {
+	if filepath.IsAbs(raw.innerPath) {
 		// Sometimes subsystems can be mounted togethger as 'cpu,cpuacct'.
-		return filepath.Join(raw.root, filepath.Base(mnt), cgPath), nil
+		return filepath.Join(raw.root, filepath.Base(mnt), raw.innerPath), nil
 	}
 
 	parentPath, err := raw.parentPath(subsystem, mnt, root)
@@ -345,7 +330,7 @@ func (raw *cgroupData) path(subsystem string) (string, error) {
 		return "", err
 	}
 
-	return filepath.Join(parentPath, cgPath), nil
+	return filepath.Join(parentPath, raw.innerPath), nil
 }
 
 func (raw *cgroupData) join(subsystem string) (string, error) {
@@ -366,9 +351,12 @@ func writeFile(dir, file, data string) error {
 	// Normally dir should not be empty, one case is that cgroup subsystem
 	// is not mounted, we will get empty dir, and we want it fail here.
 	if dir == "" {
-		return fmt.Errorf("no such directory for %s.", file)
+		return fmt.Errorf("no such directory for %s", file)
 	}
-	return ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700)
+	if err := ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700); err != nil {
+		return fmt.Errorf("failed to write %v to %v: %v", data, file, err)
+	}
+	return nil
 }
 
 func readFile(dir, file string) (string, error) {

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/cpuset.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
 )
 
 type CpusetGroup struct {
@@ -88,7 +89,7 @@ func (s *CpusetGroup) getSubsystemSettings(parent string) (cpus []byte, mems []b
 // it's parent.
 func (s *CpusetGroup) ensureParent(current, root string) error {
 	parent := filepath.Dir(current)
-	if filepath.Clean(parent) == root {
+	if libcontainerUtils.CleanPath(parent) == root {
 		return nil
 	}
 	// Avoid infinite recursion.

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/devices.go

@@ -5,6 +5,7 @@ package fs
 import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/system"
 )
 
 type DevicesGroup struct {
@@ -25,6 +26,23 @@ func (s *DevicesGroup) Apply(d *cgroupData) error {
 }
 
 func (s *DevicesGroup) Set(path string, cgroup *configs.Cgroup) error {
+	if system.RunningInUserNS() {
+		return nil
+	}
+
+	devices := cgroup.Resources.Devices
+	if len(devices) > 0 {
+		for _, dev := range devices {
+			file := "devices.deny"
+			if dev.Allow {
+				file = "devices.allow"
+			}
+			if err := writeFile(path, file, dev.CgroupString()); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
 	if !cgroup.Resources.AllowAllDevices {
 		if err := writeFile(path, "devices.deny", "a"); err != nil {
 			return err

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/memory.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
@@ -26,38 +27,75 @@ func (s *MemoryGroup) Apply(d *cgroupData) (err error) {
 	if err != nil && !cgroups.IsNotFound(err) {
 		return err
 	}
-	if memoryAssigned(d.config) {
-		if path != "" {
-			if err := os.MkdirAll(path, 0755); err != nil {
-				return err
-			}
-		}
-		// We have to set kernel memory here, as we can't change it once
-		// processes have been attached.
-		if err := s.SetKernelMemory(path, d.config); err != nil {
-			return err
-		}
+	// reset error.
+	err = nil
+	if path == "" {
+		// Invalid input.
+		return fmt.Errorf("invalid path for memory cgroups: %+v", d)
 	}
-
 	defer func() {
 		if err != nil {
 			os.RemoveAll(path)
 		}
 	}()
-
+	if !cgroups.PathExists(path) {
+		if err = os.MkdirAll(path, 0755); err != nil {
+			return err
+		}
+	}
+	if memoryAssigned(d.config) {
+		// We have to set kernel memory here, as we can't change it once
+		// processes have been attached to the cgroup.
+		if err = s.SetKernelMemory(path, d.config); err != nil {
+			return err
+		}
+	}
 	// We need to join memory cgroup after set memory limits, because
 	// kmem.limit_in_bytes can only be set when the cgroup is empty.
-	_, err = d.join("memory")
-	if err != nil && !cgroups.IsNotFound(err) {
+	if _, jerr := d.join("memory"); jerr != nil && !cgroups.IsNotFound(jerr) {
+		err = jerr
 		return err
 	}
 	return nil
 }
 
+func getModifyTime(path string) (time.Time, error) {
+	stat, err := os.Stat(path)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("failed to get memory cgroups creation time: %v", err)
+	}
+	return stat.ModTime(), nil
+}
+
 func (s *MemoryGroup) SetKernelMemory(path string, cgroup *configs.Cgroup) error {
-	// This has to be done separately because it has special constraints (it
-	// can't be done after there are processes attached to the cgroup).
-	if cgroup.Resources.KernelMemory > 0 {
+	// This has to be done separately because it has special
+	// constraints (it can only be initialized before setting up a
+	// hierarchy or adding a task to the cgroups. However, if
+	// sucessfully initialized, it can be updated anytime afterwards)
+	if cgroup.Resources.KernelMemory != 0 {
+		// Is kmem.limit_in_bytes already set?
+		// memory.kmem.max_usage_in_bytes is a read-only file. Use it to get cgroups creation time.
+		kmemCreationTime, err := getModifyTime(filepath.Join(path, "memory.kmem.max_usage_in_bytes"))
+		if err != nil {
+			return err
+		}
+		kmemLimitsUpdateTime, err := getModifyTime(filepath.Join(path, "memory.kmem.limit_in_bytes"))
+		if err != nil {
+			return err
+		}
+		// kmem.limit_in_bytes has already been set if its update time is after that of creation time.
+		// We use `!=` op instead of `>` because updates are losing precision compared to creation.
+		kmemInitialized := !kmemLimitsUpdateTime.Equal(kmemCreationTime)
+		if !kmemInitialized {
+			// If there's already tasks in the cgroup, we can't change the limit either
+			tasks, err := getCgroupParamString(path, "tasks")
+			if err != nil {
+				return err
+			}
+			if tasks != "" {
+				return fmt.Errorf("cannot set kmem.limit_in_bytes after task have joined this cgroup")
+			}
+		}
 		if err := writeFile(path, "memory.kmem.limit_in_bytes", strconv.FormatInt(cgroup.Resources.KernelMemory, 10)); err != nil {
 			return err
 		}
@@ -65,19 +103,65 @@ func (s *MemoryGroup) SetKernelMemory(path string, cgroup *configs.Cgroup) error
 	return nil
 }
 
-func (s *MemoryGroup) Set(path string, cgroup *configs.Cgroup) error {
-	if cgroup.Resources.Memory != 0 {
-		if err := writeFile(path, "memory.limit_in_bytes", strconv.FormatInt(cgroup.Resources.Memory, 10)); err != nil {
+func setMemoryAndSwap(path string, cgroup *configs.Cgroup) error {
+	// When memory and swap memory are both set, we need to handle the cases
+	// for updating container.
+	if cgroup.Resources.Memory != 0 && cgroup.Resources.MemorySwap > 0 {
+		memoryUsage, err := getMemoryData(path, "")
+		if err != nil {
 			return err
 		}
+
+		// When update memory limit, we should adapt the write sequence
+		// for memory and swap memory, so it won't fail because the new
+		// value and the old value don't fit kernel's validation.
+		if memoryUsage.Limit < uint64(cgroup.Resources.MemorySwap) {
+			if err := writeFile(path, "memory.memsw.limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemorySwap, 10)); err != nil {
+				return err
+			}
+			if err := writeFile(path, "memory.limit_in_bytes", strconv.FormatInt(cgroup.Resources.Memory, 10)); err != nil {
+				return err
+			}
+		} else {
+			if err := writeFile(path, "memory.limit_in_bytes", strconv.FormatInt(cgroup.Resources.Memory, 10)); err != nil {
+				return err
+			}
+			if err := writeFile(path, "memory.memsw.limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemorySwap, 10)); err != nil {
+				return err
+			}
+		}
+	} else {
+		if cgroup.Resources.Memory != 0 {
+			if err := writeFile(path, "memory.limit_in_bytes", strconv.FormatInt(cgroup.Resources.Memory, 10)); err != nil {
+				return err
+			}
+		}
+		if cgroup.Resources.MemorySwap > 0 {
+			if err := writeFile(path, "memory.memsw.limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemorySwap, 10)); err != nil {
+				return err
+			}
+		}
 	}
+
+	return nil
+}
+
+func (s *MemoryGroup) Set(path string, cgroup *configs.Cgroup) error {
+	if err := setMemoryAndSwap(path, cgroup); err != nil {
+		return err
+	}
+
+	if err := s.SetKernelMemory(path, cgroup); err != nil {
+		return err
+	}
+
 	if cgroup.Resources.MemoryReservation != 0 {
 		if err := writeFile(path, "memory.soft_limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemoryReservation, 10)); err != nil {
 			return err
 		}
 	}
-	if cgroup.Resources.MemorySwap > 0 {
-		if err := writeFile(path, "memory.memsw.limit_in_bytes", strconv.FormatInt(cgroup.Resources.MemorySwap, 10)); err != nil {
+	if cgroup.Resources.KernelMemoryTCP != 0 {
+		if err := writeFile(path, "memory.kmem.tcp.limit_in_bytes", strconv.FormatInt(cgroup.Resources.KernelMemoryTCP, 10)); err != nil {
 			return err
 		}
 	}
@@ -86,14 +170,14 @@ func (s *MemoryGroup) Set(path string, cgroup *configs.Cgroup) error {
 			return err
 		}
 	}
-	if cgroup.Resources.MemorySwappiness >= 0 && cgroup.Resources.MemorySwappiness <= 100 {
-		if err := writeFile(path, "memory.swappiness", strconv.FormatInt(cgroup.Resources.MemorySwappiness, 10)); err != nil {
+	if cgroup.Resources.MemorySwappiness == nil || int64(*cgroup.Resources.MemorySwappiness) == -1 {
+		return nil
+	} else if int64(*cgroup.Resources.MemorySwappiness) >= 0 && int64(*cgroup.Resources.MemorySwappiness) <= 100 {
+		if err := writeFile(path, "memory.swappiness", strconv.FormatInt(*cgroup.Resources.MemorySwappiness, 10)); err != nil {
 			return err
 		}
-	} else if cgroup.Resources.MemorySwappiness == -1 {
-		return nil
 	} else {
-		return fmt.Errorf("invalid value:%d. valid memory swappiness range is 0-100", cgroup.Resources.MemorySwappiness)
+		return fmt.Errorf("invalid value:%d. valid memory swappiness range is 0-100", int64(*cgroup.Resources.MemorySwappiness))
 	}
 
 	return nil
@@ -139,6 +223,11 @@ func (s *MemoryGroup) GetStats(path string, stats *cgroups.Stats) error {
 		return err
 	}
 	stats.MemoryStats.KernelUsage = kernelUsage
+	kernelTCPUsage, err := getMemoryData(path, "kmem.tcp")
+	if err != nil {
+		return err
+	}
+	stats.MemoryStats.KernelTCPUsage = kernelTCPUsage
 
 	return nil
 }
@@ -148,8 +237,9 @@ func memoryAssigned(cgroup *configs.Cgroup) bool {
 		cgroup.Resources.MemoryReservation != 0 ||
 		cgroup.Resources.MemorySwap > 0 ||
 		cgroup.Resources.KernelMemory > 0 ||
+		cgroup.Resources.KernelMemoryTCP > 0 ||
 		cgroup.Resources.OomKillDisable ||
-		cgroup.Resources.MemorySwappiness != -1
+		(cgroup.Resources.MemorySwappiness != nil && *cgroup.Resources.MemorySwappiness != -1)
 }
 
 func getMemoryData(path, name string) (cgroups.MemoryData, error) {
@@ -162,6 +252,7 @@ func getMemoryData(path, name string) (cgroups.MemoryData, error) {
 	usage := strings.Join([]string{moduleName, "usage_in_bytes"}, ".")
 	maxUsage := strings.Join([]string{moduleName, "max_usage_in_bytes"}, ".")
 	failcnt := strings.Join([]string{moduleName, "failcnt"}, ".")
+	limit := strings.Join([]string{moduleName, "limit_in_bytes"}, ".")
 
 	value, err := getCgroupParamUint(path, usage)
 	if err != nil {
@@ -187,6 +278,14 @@ func getMemoryData(path, name string) (cgroups.MemoryData, error) {
 		return cgroups.MemoryData{}, fmt.Errorf("failed to parse %s - %v", failcnt, err)
 	}
 	memoryData.Failcnt = value
+	value, err = getCgroupParamUint(path, limit)
+	if err != nil {
+		if moduleName != "memory" && os.IsNotExist(err) {
+			return cgroups.MemoryData{}, nil
+		}
+		return cgroups.MemoryData{}, fmt.Errorf("failed to parse %s - %v", limit, err)
+	}
+	memoryData.Limit = value
 
 	return memoryData, nil
 }

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/name.go

@@ -9,6 +9,7 @@ import (
 
 type NameGroup struct {
 	GroupName string
+	Join      bool
 }
 
 func (s *NameGroup) Name() string {
@@ -16,6 +17,10 @@ func (s *NameGroup) Name() string {
 }
 
 func (s *NameGroup) Apply(d *cgroupData) error {
+	if s.Join {
+		// ignore errors if the named cgroup does not exist
+		d.join(s.GroupName)
+	}
 	return nil
 }
 
@@ -24,6 +29,9 @@ func (s *NameGroup) Set(path string, cgroup *configs.Cgroup) error {
 }
 
 func (s *NameGroup) Remove(d *cgroupData) error {
+	if s.Join {
+		removePath(d.path(s.GroupName))
+	}
 	return nil
 }
 

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/pids.go

@@ -4,6 +4,7 @@ package fs
 
 import (
 	"fmt"
+	"path/filepath"
 	"strconv"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
@@ -47,11 +48,26 @@ func (s *PidsGroup) Remove(d *cgroupData) error {
 }
 
 func (s *PidsGroup) GetStats(path string, stats *cgroups.Stats) error {
-	value, err := getCgroupParamUint(path, "pids.current")
+	current, err := getCgroupParamUint(path, "pids.current")
 	if err != nil {
 		return fmt.Errorf("failed to parse pids.current - %s", err)
 	}
 
-	stats.PidsStats.Current = value
+	maxString, err := getCgroupParamString(path, "pids.max")
+	if err != nil {
+		return fmt.Errorf("failed to parse pids.max - %s", err)
+	}
+
+	// Default if pids.max == "max" is 0 -- which represents "no limit".
+	var max uint64
+	if maxString != "max" {
+		max, err = parseUint(maxString, 10, 64)
+		if err != nil {
+			return fmt.Errorf("failed to parse pids.max - unable to parse %q as a uint from Cgroup file %q", maxString, filepath.Join(path, "pids.max"))
+		}
+	}
+
+	stats.PidsStats.Current = current
+	stats.PidsStats.Limit = max
 	return nil
 }

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/utils.go

@@ -12,7 +12,6 @@ import (
 )
 
 var (
-	ErrNotSupportStat = errors.New("stats are not supported for subsystem")
 	ErrNotValidFormat = errors.New("line is not a valid key value format")
 )
 

vendor/github.com/opencontainers/runc/libcontainer/cgroups/stats.go

@@ -11,6 +11,7 @@ type ThrottlingData struct {
 	ThrottledTime uint64 `json:"throttled_time,omitempty"`
 }
 
+// CpuUsage denotes the usage of a CPU.
 // All CPU stats are aggregate since container inception.
 type CpuUsage struct {
 	// Total CPU time consumed.
@@ -36,7 +37,9 @@ type MemoryData struct {
 	Usage    uint64 `json:"usage,omitempty"`
 	MaxUsage uint64 `json:"max_usage,omitempty"`
 	Failcnt  uint64 `json:"failcnt"`
+	Limit    uint64 `json:"limit"`
 }
+
 type MemoryStats struct {
 	// memory used for cache
 	Cache uint64 `json:"cache,omitempty"`
@@ -44,14 +47,19 @@ type MemoryStats struct {
 	Usage MemoryData `json:"usage,omitempty"`
 	// usage of memory + swap
 	SwapUsage MemoryData `json:"swap_usage,omitempty"`
-	// usafe of kernel memory
-	KernelUsage MemoryData        `json:"kernel_usage,omitempty"`
-	Stats       map[string]uint64 `json:"stats,omitempty"`
+	// usage of kernel memory
+	KernelUsage MemoryData `json:"kernel_usage,omitempty"`
+	// usage of kernel TCP memory
+	KernelTCPUsage MemoryData `json:"kernel_tcp_usage,omitempty"`
+
+	Stats map[string]uint64 `json:"stats,omitempty"`
 }
 
 type PidsStats struct {
 	// number of pids in the cgroup
 	Current uint64 `json:"current,omitempty"`
+	// active pids hard limit
+	Limit uint64 `json:"limit,omitempty"`
 }
 
 type BlkioStatEntry struct {
@@ -78,7 +86,7 @@ type HugetlbStats struct {
 	Usage uint64 `json:"usage,omitempty"`
 	// maximum usage ever recorded.
 	MaxUsage uint64 `json:"max_usage,omitempty"`
-	// number of times htgetlb usage allocation failure.
+	// number of times hugetlb usage allocation failure.
 	Failcnt uint64 `json:"failcnt"`
 }
 

vendor/github.com/opencontainers/runc/libcontainer/cgroups/utils.go

@@ -5,6 +5,7 @@ package cgroups
 import (
 	"bufio"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -12,17 +13,19 @@ import (
 	"strings"
 	"time"
 
-	"github.com/docker/docker/pkg/mount"
 	"github.com/docker/go-units"
 )
 
 const cgroupNamePrefix = "name="
 
-// https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt
+// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
 func FindCgroupMountpoint(subsystem string) (string, error) {
 	// We are not using mount.GetMounts() because it's super-inefficient,
 	// parsing it directly sped up x10 times because of not using Sscanf.
 	// It was one of two major performance drawbacks in container start.
+	if !isSubsystemAvailable(subsystem) {
+		return "", NewNotFoundError(subsystem)
+	}
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return "", err
@@ -47,6 +50,9 @@ func FindCgroupMountpoint(subsystem string) (string, error) {
 }
 
 func FindCgroupMountpointAndRoot(subsystem string) (string, string, error) {
+	if !isSubsystemAvailable(subsystem) {
+		return "", "", NewNotFoundError(subsystem)
+	}
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return "", "", err
@@ -70,6 +76,15 @@ func FindCgroupMountpointAndRoot(subsystem string) (string, string, error) {
 	return "", "", NewNotFoundError(subsystem)
 }
 
+func isSubsystemAvailable(subsystem string) bool {
+	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
+	if err != nil {
+		return false
+	}
+	_, avail := cgroups[subsystem]
+	return avail
+}
+
 func FindCgroupMountpointDir() (string, error) {
 	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
@@ -121,42 +136,63 @@ func (m Mount) GetThisCgroupDir(cgroups map[string]string) (string, error) {
 	return getControllerPath(m.Subsystems[0], cgroups)
 }
 
+func getCgroupMountsHelper(ss map[string]bool, mi io.Reader) ([]Mount, error) {
+	res := make([]Mount, 0, len(ss))
+	scanner := bufio.NewScanner(mi)
+	numFound := 0
+	for scanner.Scan() && numFound < len(ss) {
+		txt := scanner.Text()
+		sepIdx := strings.Index(txt, " - ")
+		if sepIdx == -1 {
+			return nil, fmt.Errorf("invalid mountinfo format")
+		}
+		if txt[sepIdx+3:sepIdx+9] != "cgroup" {
+			continue
+		}
+		fields := strings.Split(txt, " ")
+		m := Mount{
+			Mountpoint: fields[4],
+			Root:       fields[3],
+		}
+		for _, opt := range strings.Split(fields[len(fields)-1], ",") {
+			if !ss[opt] {
+				continue
+			}
+			if strings.HasPrefix(opt, cgroupNamePrefix) {
+				m.Subsystems = append(m.Subsystems, opt[len(cgroupNamePrefix):])
+			} else {
+				m.Subsystems = append(m.Subsystems, opt)
+			}
+			numFound++
+		}
+		res = append(res, m)
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
 func GetCgroupMounts() ([]Mount, error) {
-	mounts, err := mount.GetMounts()
+	f, err := os.Open("/proc/self/mountinfo")
 	if err != nil {
 		return nil, err
 	}
+	defer f.Close()
 
-	all, err := GetAllSubsystems()
+	all, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return nil, err
 	}
 
 	allMap := make(map[string]bool)
-	for _, s := range all {
+	for s := range all {
 		allMap[s] = true
 	}
-
-	res := []Mount{}
-	for _, mount := range mounts {
-		if mount.Fstype == "cgroup" {
-			m := Mount{Mountpoint: mount.Mountpoint, Root: mount.Root}
-
-			for _, opt := range strings.Split(mount.VfsOpts, ",") {
-				if strings.HasPrefix(opt, cgroupNamePrefix) {
-					m.Subsystems = append(m.Subsystems, opt[len(cgroupNamePrefix):])
-				}
-				if allMap[opt] {
-					m.Subsystems = append(m.Subsystems, opt)
-				}
-			}
-			res = append(res, m)
-		}
-	}
-	return res, nil
+	return getCgroupMountsHelper(allMap, f)
 }
 
-// Returns all the cgroup subsystems supported by the kernel
+// GetAllSubsystems returns all the cgroup subsystems supported by the kernel
 func GetAllSubsystems() ([]string, error) {
 	f, err := os.Open("/proc/cgroups")
 	if err != nil {
@@ -182,7 +218,7 @@ func GetAllSubsystems() ([]string, error) {
 	return subsystems, nil
 }
 
-// Returns the relative path to the cgroup docker is running in.
+// GetThisCgroupDir returns the relative path to the cgroup docker is running in.
 func GetThisCgroupDir(subsystem string) (string, error) {
 	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
@@ -226,6 +262,8 @@ func readProcsFile(dir string) ([]int, error) {
 	return out, nil
 }
 
+// ParseCgroupFile parses the given cgroup file, typically from
+// /proc/<pid>/cgroup, into a map of subgroups to cgroup names.
 func ParseCgroupFile(path string) (map[string]string, error) {
 	f, err := os.Open(path)
 	if err != nil {
@@ -233,7 +271,12 @@ func ParseCgroupFile(path string) (map[string]string, error) {
 	}
 	defer f.Close()
 
-	s := bufio.NewScanner(f)
+	return parseCgroupFromReader(f)
+}
+
+// helper function for ParseCgroupFile to make testing easier
+func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
+	s := bufio.NewScanner(r)
 	cgroups := make(map[string]string)
 
 	for s.Scan() {
@@ -242,7 +285,16 @@ func ParseCgroupFile(path string) (map[string]string, error) {
 		}
 
 		text := s.Text()
-		parts := strings.Split(text, ":")
+		// from cgroups(7):
+		// /proc/[pid]/cgroup
+		// ...
+		// For each cgroup hierarchy ... there is one entry
+		// containing three colon-separated fields of the form:
+		//     hierarchy-ID:subsystem-list:cgroup-path
+		parts := strings.SplitN(text, ":", 3)
+		if len(parts) < 3 {
+			return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
+		}
 
 		for _, subs := range strings.Split(parts[1], ",") {
 			cgroups[subs] = parts[2]
@@ -309,7 +361,7 @@ func RemovePaths(paths map[string]string) (err error) {
 			return nil
 		}
 	}
-	return fmt.Errorf("Failed to remove paths: %s", paths)
+	return fmt.Errorf("Failed to remove paths: %v", paths)
 }
 
 func GetHugePageSize() ([]string, error) {