diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cab5a41d..7382d096 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -2,11 +2,11 @@ name: CI
 on:
   push:
     branches:
-      - master
+      - main
       - 'release/**'
   pull_request:
     branches:
-      - master
+      - main
       - 'release/**'
 
 jobs:
@@ -23,9 +23,9 @@ jobs:
       # Install Go
       #
       - name: Install Go
-        uses: actions/setup-go@v1
+        uses: actions/setup-go@v2
         with:
-          go-version: '1.15'
+          go-version: '1.16.x'
 
       - name: Set env
         shell: bash
@@ -88,9 +88,9 @@ jobs:
 
     steps:
       - name: Install Go
-        uses: actions/setup-go@v1
+        uses: actions/setup-go@v2
         with:
-          go-version: '1.15'
+          go-version: '1.16.x'
 
       - name: Set env
         shell: bash
diff --git a/README.md b/README.md
index d4b09f3d..fc2c7a9b 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # cgroups
 
 [![Build Status](https://github.com/containerd/cgroups/workflows/CI/badge.svg)](https://github.com/containerd/cgroups/actions?query=workflow%3ACI)
-[![codecov](https://codecov.io/gh/containerd/cgroups/branch/master/graph/badge.svg)](https://codecov.io/gh/containerd/cgroups)
+[![codecov](https://codecov.io/gh/containerd/cgroups/branch/main/graph/badge.svg)](https://codecov.io/gh/containerd/cgroups)
 [![GoDoc](https://godoc.org/github.com/containerd/cgroups?status.svg)](https://godoc.org/github.com/containerd/cgroups)
 [![Go Report Card](https://goreportcard.com/badge/github.com/containerd/cgroups)](https://goreportcard.com/report/github.com/containerd/cgroups)
 
@@ -142,8 +142,8 @@ All static path should not include `/sys/fs/cgroup/` prefix, it should start wit
 Cgroups is a containerd sub-project, licensed under the [Apache 2.0 license](./LICENSE).
 As a containerd sub-project, you will find the:
 
- * [Project governance](https://github.com/containerd/project/blob/master/GOVERNANCE.md),
- * [Maintainers](https://github.com/containerd/project/blob/master/MAINTAINERS),
- * and [Contributing guidelines](https://github.com/containerd/project/blob/master/CONTRIBUTING.md)
+ * [Project governance](https://github.com/containerd/project/blob/main/GOVERNANCE.md),
+ * [Maintainers](https://github.com/containerd/project/blob/main/MAINTAINERS),
+ * and [Contributing guidelines](https://github.com/containerd/project/blob/main/CONTRIBUTING.md)
 
 information in our [`containerd/project`](https://github.com/containerd/project) repository.
diff --git a/blkio.go b/blkio.go
index a837e19f..f59c75bb 100644
--- a/blkio.go
+++ b/blkio.go
@@ -130,7 +130,7 @@ func (b *blkioController) Stat(path string, stats *v1.Metrics) error {
 		}
 	}
 
-	f, err := os.Open(filepath.Join(b.procRoot, "diskstats"))
+	f, err := os.Open(filepath.Join(b.procRoot, "partitions"))
 	if err != nil {
 		return err
 	}
@@ -335,7 +335,10 @@ func getDevices(r io.Reader) (map[deviceKey]string, error) {
 		s       = bufio.NewScanner(r)
 		devices = make(map[deviceKey]string)
 	)
-	for s.Scan() {
+	for i := 0; s.Scan(); i++ {
+		if i < 2 {
+			continue
+		}
 		fields := strings.Fields(s.Text())
 		major, err := strconv.Atoi(fields[0])
 		if err != nil {
@@ -352,7 +355,7 @@ func getDevices(r io.Reader) (map[deviceKey]string, error) {
 		if _, ok := devices[key]; ok {
 			continue
 		}
-		devices[key] = filepath.Join("/dev", fields[2])
+		devices[key] = filepath.Join("/dev", fields[3])
 	}
 	return devices, s.Err()
 }
diff --git a/blkio_test.go b/blkio_test.go
index 36b08957..07b2a967 100644
--- a/blkio_test.go
+++ b/blkio_test.go
@@ -24,18 +24,19 @@ import (
 	v1 "github.com/containerd/cgroups/stats/v1"
 )
 
-const data = `   7       0 loop0 0 0 0 0 0 0 0 0 0 0 0
-   7       1 loop1 0 0 0 0 0 0 0 0 0 0 0
-   7       2 loop2 0 0 0 0 0 0 0 0 0 0 0
-   7       3 loop3 0 0 0 0 0 0 0 0 0 0 0
-   7       4 loop4 0 0 0 0 0 0 0 0 0 0 0
-   7       5 loop5 0 0 0 0 0 0 0 0 0 0 0
-   7       6 loop6 0 0 0 0 0 0 0 0 0 0 0
-   7       7 loop7 0 0 0 0 0 0 0 0 0 0 0
-   8       0 sda 1892042 187697 63489222 1246284 1389086 2887005 134903104 11390608 1 1068060 12692228
-   8       1 sda1 1762875 37086 61241570 1200512 1270037 2444415 131214808 11152764 1 882624 12409308
-   8       2 sda2 2 0 4 0 0 0 0 0 0 0 0
-   8       5 sda5 129102 150611 2244440 45716 18447 442590 3688296 67268 0 62584 112984`
+const data = `major minor  #blocks  name
+
+   7        0          4 loop0
+   7        1     163456 loop1
+   7        2     149616 loop2
+   7        3     147684 loop3
+   7        4     122572 loop4
+   7        5       8936 loop5
+   7        6      31464 loop6
+   7        7     182432 loop7
+ 259        0  937692504 nvme0n1
+ 259        1      31744 nvme0n1p1
+`
 
 func TestGetDevices(t *testing.T) {
 	r := strings.NewReader(data)
@@ -43,13 +44,18 @@ func TestGetDevices(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	name, ok := devices[deviceKey{8, 0}]
-	if !ok {
-		t.Fatal("no device found for 8,0")
-	}
-	const expected = "/dev/sda"
-	if name != expected {
-		t.Fatalf("expected device name %q but received %q", expected, name)
+	for dev, expected := range map[deviceKey]string{
+		deviceKey{7, 0}: "/dev/loop0",
+		deviceKey{259, 0}: "/dev/nvme0n1",
+		deviceKey{259, 1}: "/dev/nvme0n1p1",
+	} {
+		name, ok := devices[dev]
+		if !ok {
+			t.Fatalf("no device found for %d:%d", dev.major, dev.minor)
+		}
+		if name != expected {
+			t.Fatalf("expected device name %q but received %q", expected, name)
+		}
 	}
 }
 
diff --git a/cgroup.go b/cgroup.go
index e0e014b2..0fab1cec 100644
--- a/cgroup.go
+++ b/cgroup.go
@@ -17,6 +17,7 @@
 package cgroups
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -25,8 +26,8 @@ import (
 	"sync"
 
 	v1 "github.com/containerd/cgroups/stats/v1"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/pkg/errors"
+
+	"github.com/opencontainers/runtime-spec/specs-go"
 )
 
 // New returns a new control via the cgroup cgroups interface
@@ -83,7 +84,7 @@ func Load(hierarchy Hierarchy, path Path, opts ...InitOpts) (Cgroup, error) {
 	for _, s := range pathers(subsystems) {
 		p, err := path(s.Name())
 		if err != nil {
-			if os.IsNotExist(errors.Cause(err)) {
+			if  errors.Is(err, os.ErrNotExist) {
 				return nil, ErrCgroupDeleted
 			}
 			if err == ErrControllerNotActive {
@@ -149,38 +150,50 @@ func (c *cgroup) Subsystems() []Subsystem {
 	return c.subsystems
 }
 
-// Add moves the provided process into the new cgroup
-func (c *cgroup) Add(process Process) error {
-	if process.Pid <= 0 {
-		return ErrInvalidPid
+func (c *cgroup) subsystemsFilter(subsystems ...Name) []Subsystem {
+	if len(subsystems) == 0 {
+		return c.subsystems
 	}
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	if c.err != nil {
-		return c.err
-	}
-	return c.add(process)
-}
 
-func (c *cgroup) add(process Process) error {
-	for _, s := range pathers(c.subsystems) {
-		p, err := c.path(s.Name())
-		if err != nil {
-			return err
-		}
-		if err := retryingWriteFile(
-			filepath.Join(s.Path(p), cgroupProcs),
-			[]byte(strconv.Itoa(process.Pid)),
-			defaultFilePerm,
-		); err != nil {
-			return err
+	var filteredSubsystems = []Subsystem{}
+	for _, s := range c.subsystems {
+		for _, f := range subsystems {
+			if s.Name() == f {
+				filteredSubsystems = append(filteredSubsystems, s)
+				break
+			}
 		}
 	}
-	return nil
+
+	return filteredSubsystems
+}
+
+// Add moves the provided process into the new cgroup.
+// Without additional arguments, the process is added to all the cgroup subsystems.
+// When giving Add a list of subsystem names, the process is only added to those
+// subsystems, provided that they are active in the targeted cgroup.
+func (c *cgroup) Add(process Process, subsystems ...Name) error {
+	return c.add(process, cgroupProcs, subsystems...)
+}
+
+// AddProc moves the provided process id into the new cgroup.
+// Without additional arguments, the process with the given id is added to all
+// the cgroup subsystems. When giving AddProc a list of subsystem names, the process
+// id is only added to those subsystems, provided that they are active in the targeted
+// cgroup.
+func (c *cgroup) AddProc(pid uint64, subsystems ...Name) error {
+	return c.add(Process{Pid: int(pid)}, cgroupProcs, subsystems...)
 }
 
-// AddTask moves the provided tasks (threads) into the new cgroup
-func (c *cgroup) AddTask(process Process) error {
+// AddTask moves the provided tasks (threads) into the new cgroup.
+// Without additional arguments, the task is added to all the cgroup subsystems.
+// When giving AddTask a list of subsystem names, the task is only added to those
+// subsystems, provided that they are active in the targeted cgroup.
+func (c *cgroup) AddTask(process Process, subsystems ...Name) error {
+	return c.add(process, cgroupTasks, subsystems...)
+}
+
+func (c *cgroup) add(process Process, pType procType, subsystems ...Name) error {
 	if process.Pid <= 0 {
 		return ErrInvalidPid
 	}
@@ -189,20 +202,17 @@ func (c *cgroup) AddTask(process Process) error {
 	if c.err != nil {
 		return c.err
 	}
-	return c.addTask(process)
-}
-
-func (c *cgroup) addTask(process Process) error {
-	for _, s := range pathers(c.subsystems) {
+	for _, s := range pathers(c.subsystemsFilter(subsystems...)) {
 		p, err := c.path(s.Name())
 		if err != nil {
 			return err
 		}
-		if err := retryingWriteFile(
-			filepath.Join(s.Path(p), cgroupTasks),
+		err = retryingWriteFile(
+			filepath.Join(s.Path(p), pType),
 			[]byte(strconv.Itoa(process.Pid)),
 			defaultFilePerm,
-		); err != nil {
+		)
+		if err != nil {
 			return err
 		}
 	}
@@ -326,39 +336,7 @@ func (c *cgroup) Processes(subsystem Name, recursive bool) ([]Process, error) {
 	if c.err != nil {
 		return nil, c.err
 	}
-	return c.processes(subsystem, recursive)
-}
-
-func (c *cgroup) processes(subsystem Name, recursive bool) ([]Process, error) {
-	s := c.getSubsystem(subsystem)
-	sp, err := c.path(subsystem)
-	if err != nil {
-		return nil, err
-	}
-	path := s.(pather).Path(sp)
-	var processes []Process
-	err = filepath.Walk(path, func(p string, info os.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-		if !recursive && info.IsDir() {
-			if p == path {
-				return nil
-			}
-			return filepath.SkipDir
-		}
-		dir, name := filepath.Split(p)
-		if name != cgroupProcs {
-			return nil
-		}
-		procs, err := readPids(dir, subsystem)
-		if err != nil {
-			return err
-		}
-		processes = append(processes, procs...)
-		return nil
-	})
-	return processes, err
+	return c.processes(subsystem, recursive, cgroupProcs)
 }
 
 // Tasks returns the tasks running inside the cgroup along
@@ -369,17 +347,20 @@ func (c *cgroup) Tasks(subsystem Name, recursive bool) ([]Task, error) {
 	if c.err != nil {
 		return nil, c.err
 	}
-	return c.tasks(subsystem, recursive)
+	return c.processes(subsystem, recursive, cgroupTasks)
 }
 
-func (c *cgroup) tasks(subsystem Name, recursive bool) ([]Task, error) {
+func (c *cgroup) processes(subsystem Name, recursive bool, pType procType) ([]Process, error) {
 	s := c.getSubsystem(subsystem)
 	sp, err := c.path(subsystem)
 	if err != nil {
 		return nil, err
 	}
+	if s == nil {
+		return nil, fmt.Errorf("cgroups: %s doesn't exist in %s subsystem", sp, subsystem)
+	}
 	path := s.(pather).Path(sp)
-	var tasks []Task
+	var processes []Process
 	err = filepath.Walk(path, func(p string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
@@ -391,17 +372,17 @@ func (c *cgroup) tasks(subsystem Name, recursive bool) ([]Task, error) {
 			return filepath.SkipDir
 		}
 		dir, name := filepath.Split(p)
-		if name != cgroupTasks {
+		if name != pType {
 			return nil
 		}
-		procs, err := readTasksPids(dir, subsystem)
+		procs, err := readPids(dir, subsystem, pType)
 		if err != nil {
 			return err
 		}
-		tasks = append(tasks, procs...)
+		processes = append(processes, procs...)
 		return nil
 	})
-	return tasks, err
+	return processes, err
 }
 
 // Freeze freezes the entire cgroup and all the processes inside it
@@ -511,7 +492,7 @@ func (c *cgroup) MoveTo(destination Cgroup) error {
 		return c.err
 	}
 	for _, s := range c.subsystems {
-		processes, err := c.processes(s.Name(), true)
+		processes, err := c.processes(s.Name(), true, cgroupProcs)
 		if err != nil {
 			return err
 		}
diff --git a/cgroup_test.go b/cgroup_test.go
index b8971055..1b170fdb 100644
--- a/cgroup_test.go
+++ b/cgroup_test.go
@@ -101,6 +101,63 @@ func TestAdd(t *testing.T) {
 	}
 }
 
+func TestAddFilteredSubsystems(t *testing.T) {
+	mock, err := newMock()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mock.delete()
+	control, err := New(mock.hierarchy, StaticPath("test"), &specs.LinuxResources{})
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	filteredSubsystems := []Name{"memory", "cpu"}
+	if err := control.Add(Process{Pid: 1234}, filteredSubsystems...); err != nil {
+		t.Error(err)
+		return
+	}
+
+	for _, s := range filteredSubsystems {
+		if err := checkPid(mock, filepath.Join(string(s), "test"), 1234); err != nil {
+			t.Error(err)
+			return
+		}
+	}
+
+	if err := checkPid(mock, filepath.Join("devices", "test"), 1234); err == nil {
+		t.Error("Pid should not be added to the devices subsystem")
+		return
+	}
+
+	bogusSubsystems := append(filteredSubsystems, "bogus")
+	if err := control.Add(Process{Pid: 5678}, bogusSubsystems...); err != nil {
+		t.Error(err)
+		return
+	}
+
+	for _, s := range filteredSubsystems {
+		if err := checkPid(mock, filepath.Join(string(s), "test"), 5678); err != nil {
+			t.Error(err)
+			return
+		}
+	}
+
+	nilSubsystems := []Name{}
+	if err := control.Add(Process{Pid: 9012}, nilSubsystems...); err != nil {
+		t.Error(err)
+		return
+	}
+
+	for _, s := range Subsystems() {
+		if err := checkPid(mock, filepath.Join(string(s), "test"), 9012); err != nil {
+			t.Error(err)
+			return
+		}
+	}
+}
+
 func TestAddTask(t *testing.T) {
 	mock, err := newMock()
 	if err != nil {
@@ -124,6 +181,48 @@ func TestAddTask(t *testing.T) {
 	}
 }
 
+func TestAddTaskFilteredSubsystems(t *testing.T) {
+	mock, err := newMock()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mock.delete()
+	control, err := New(mock.hierarchy, StaticPath("test"), &specs.LinuxResources{})
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	filteredSubsystems := []Name{"memory", "cpu"}
+	if err := control.AddTask(Process{Pid: 1234}, filteredSubsystems...); err != nil {
+		t.Error(err)
+		return
+	}
+	for _, s := range filteredSubsystems {
+		if err := checkTaskid(mock, filepath.Join(string(s), "test"), 1234); err != nil {
+			t.Error(err)
+			return
+		}
+	}
+
+	if err := checkTaskid(mock, filepath.Join("devices", "test"), 1234); err == nil {
+		t.Error("Task should not be added to the devices subsystem")
+		return
+	}
+
+	bogusSubsystems := append(filteredSubsystems, "bogus")
+	if err := control.AddTask(Process{Pid: 5678}, bogusSubsystems...); err != nil {
+		t.Error(err)
+		return
+	}
+
+	for _, s := range filteredSubsystems {
+		if err := checkTaskid(mock, filepath.Join(string(s), "test"), 5678); err != nil {
+			t.Error(err)
+			return
+		}
+	}
+}
+
 func TestListPids(t *testing.T) {
 	mock, err := newMock()
 	if err != nil {
diff --git a/control.go b/control.go
index a4cb9b83..5fcaac6d 100644
--- a/control.go
+++ b/control.go
@@ -23,10 +23,12 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
+type procType = string
+
 const (
-	cgroupProcs    = "cgroup.procs"
-	cgroupTasks    = "tasks"
-	defaultDirPerm = 0755
+	cgroupProcs    procType = "cgroup.procs"
+	cgroupTasks    procType = "tasks"
+	defaultDirPerm          = 0755
 )
 
 // defaultFilePerm is a var so that the test framework can change the filemode
@@ -37,32 +39,37 @@ const (
 var defaultFilePerm = os.FileMode(0)
 
 type Process struct {
-	// Subsystem is the name of the subsystem that the process is in
+	// Subsystem is the name of the subsystem that the process / task is in.
 	Subsystem Name
-	// Pid is the process id of the process
+	// Pid is the process id of the process / task.
 	Pid int
-	// Path is the full path of the subsystem and location that the process is in
+	// Path is the full path of the subsystem and location that the process / task is in.
 	Path string
 }
 
-type Task struct {
-	// Subsystem is the name of the subsystem that the task is in
-	Subsystem Name
-	// Pid is the process id of the task
-	Pid int
-	// Path is the full path of the subsystem and location that the task is in
-	Path string
-}
+type Task = Process
 
 // Cgroup handles interactions with the individual groups to perform
 // actions on them as them main interface to this cgroup package
 type Cgroup interface {
 	// New creates a new cgroup under the calling cgroup
 	New(string, *specs.LinuxResources) (Cgroup, error)
-	// Add adds a process to the cgroup (cgroup.procs)
-	Add(Process) error
-	// AddTask adds a process to the cgroup (tasks)
-	AddTask(Process) error
+	// Add adds a process to the cgroup (cgroup.procs). Without additional arguments,
+	// the process is added to all the cgroup subsystems. When giving Add a list of
+	// subsystem names, the process is only added to those subsystems, provided that
+	// they are active in the targeted cgroup.
+	Add(Process, ...Name) error
+	// AddProc adds the process with the given id to the cgroup (cgroup.procs).
+	// Without additional arguments, the process with the given id is added to all
+	// the cgroup subsystems. When giving AddProc a list of subsystem names, the process
+	// id is only added to those subsystems, provided that they are active in the targeted
+	// cgroup.
+	AddProc(uint64, ...Name) error
+	// AddTask adds a process to the cgroup (tasks). Without additional arguments, the
+	// task is added to all the cgroup subsystems. When giving AddTask a list of subsystem
+	// names, the task is only added to those subsystems, provided that they are active in
+	// the targeted cgroup.
+	AddTask(Process, ...Name) error
 	// Delete removes the cgroup as a whole
 	Delete() error
 	// MoveTo moves all the processes under the calling cgroup to the provided one
diff --git a/go.mod b/go.mod
index eed71ffb..80d3f6ea 100644
--- a/go.mod
+++ b/go.mod
@@ -1,18 +1,18 @@
 module github.com/containerd/cgroups
 
-go 1.13
+go 1.16
 
 require (
 	github.com/cilium/ebpf v0.4.0
-	github.com/coreos/go-systemd/v22 v22.1.0
+	github.com/coreos/go-systemd/v22 v22.3.2
 	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
 	github.com/docker/go-units v0.4.0
-	github.com/godbus/dbus/v5 v5.0.3
+	github.com/godbus/dbus/v5 v5.0.4
 	github.com/gogo/protobuf v1.3.2
 	github.com/opencontainers/runtime-spec v1.0.2
-	github.com/pkg/errors v0.9.1
-	github.com/sirupsen/logrus v1.7.0
-	github.com/stretchr/testify v1.6.1
+	github.com/sirupsen/logrus v1.8.1
+	github.com/stretchr/testify v1.7.0
 	github.com/urfave/cli v1.22.2
-	golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c
+	go.uber.org/goleak v1.1.12
+	golang.org/x/sys v0.0.0-20210510120138-977fb7262007
 )
diff --git a/go.sum b/go.sum
index f0861023..cda30b49 100644
--- a/go.sum
+++ b/go.sum
@@ -1,8 +1,8 @@
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/cilium/ebpf v0.4.0 h1:QlHdikaxALkqWasW8hAC1mfR0jdmvbfaBdBPFmRSglA=
 github.com/cilium/ebpf v0.4.0/go.mod h1:4tRaxcgiL706VnOzHOdBlY8IEAIdxINsQBcU4xJJXRs=
-github.com/coreos/go-systemd/v22 v22.1.0 h1:kq/SbG2BCKLkDKkjQf5OWwKWUKj1lgs3lFI4PxnR5lg=
-github.com/coreos/go-systemd/v22 v22.1.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+1atmu1JpKERPPk=
+github.com/coreos/go-systemd/v22 v22.3.2 h1:D9/bQk5vlXQFZ6Kwuu6zaiXJ9oTPe68++AzAJc1DzSI=
+github.com/coreos/go-systemd/v22 v22.3.2/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/cpuguy83/go-md2man/v2 v2.0.0 h1:EoUDS0afbrsXAZ9YQ9jdu/mZ2sXgT1/2yyNng4PGlyM=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
@@ -13,14 +13,15 @@ github.com/docker/go-units v0.4.0 h1:3uh0PgVws3nIA0Q+MwDC8yjEPf9zjRfZZWXZYDct3Tw
 github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/frankban/quicktest v1.11.3 h1:8sXhOn0uLys67V8EsXLc6eszDs8VXWxL3iRvebPhedY=
 github.com/frankban/quicktest v1.11.3/go.mod h1:wRf/ReqHper53s+kmmSZizM8NamnL3IM0I9ntUbOk+k=
-github.com/godbus/dbus/v5 v5.0.3 h1:ZqHaoEF7TBzh4jzPmqVhE/5A1z9of6orkAe5uHoAeME=
-github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/godbus/dbus/v5 v5.0.4 h1:9349emZab16e7zQvpmsbtjc18ykshndd8y2PG3sgJbA=
+github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/google/go-cmp v0.5.4 h1:L8R9j+yAqZuZjsqh/z+F1NCffTKKLShY6zXTItVIZ8M=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -28,55 +29,70 @@ github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/opencontainers/runtime-spec v1.0.2 h1:UfAcuLBJB9Coz72x1hgl8O5RVzTdNiaglX6v2DM6FI0=
 github.com/opencontainers/runtime-spec v1.0.2/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
-github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
-github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday/v2 v2.0.1 h1:lPqVAte+HuHNfhJ/0LC98ESWRz8afy9tM/0RK8m9o+Q=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
-github.com/sirupsen/logrus v1.7.0 h1:ShrD1U9pZB12TX0cVy0DtePoCH97K8EtX+mg7ZARUtM=
-github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
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 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
-github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
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 github.com/urfave/cli v1.22.2 h1:gsqYFH8bb9ekPA12kRo0hfjngWQjkJPlN9R0N78BoUo=
 github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+go.uber.org/goleak v1.1.12 h1:gZAh5/EyT/HQwlpkCy6wTpqfH9H8Lz8zbm3dZh+OyzA=
+go.uber.org/goleak v1.1.12/go.mod h1:cwTWslyiVhfpKIDGSZEM2HlOvcqm+tG4zioyIeLoqMQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
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 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
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 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
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 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
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 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/opts.go b/opts.go
index a1449e29..1e428d04 100644
--- a/opts.go
+++ b/opts.go
@@ -17,7 +17,7 @@
 package cgroups
 
 import (
-	"github.com/pkg/errors"
+	"errors"
 )
 
 var (
diff --git a/paths.go b/paths.go
index 27197eca..bddc4e9c 100644
--- a/paths.go
+++ b/paths.go
@@ -17,10 +17,9 @@
 package cgroups
 
 import (
+	"errors"
 	"fmt"
 	"path/filepath"
-
-	"github.com/pkg/errors"
 )
 
 type Path func(subsystem Name) (string, error)
@@ -39,7 +38,7 @@ func StaticPath(path string) Path {
 // NestedPath will nest the cgroups based on the calling processes cgroup
 // placing its child processes inside its own path
 func NestedPath(suffix string) Path {
-	paths, err := parseCgroupFile("/proc/self/cgroup")
+	paths, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return errorPath(err)
 	}
@@ -50,9 +49,9 @@ func NestedPath(suffix string) Path {
 // This is commonly used for the Load function to restore an existing container
 func PidPath(pid int) Path {
 	p := fmt.Sprintf("/proc/%d/cgroup", pid)
-	paths, err := parseCgroupFile(p)
+	paths, err := ParseCgroupFile(p)
 	if err != nil {
-		return errorPath(errors.Wrapf(err, "parse cgroup file %s", p))
+		return errorPath(fmt.Errorf("parse cgroup file %s: %w", p, err))
 	}
 	return existingPath(paths, "")
 }
diff --git a/paths_test.go b/paths_test.go
index 6860dee0..9dd2898d 100644
--- a/paths_test.go
+++ b/paths_test.go
@@ -41,7 +41,7 @@ func TestSelfPath(t *testing.T) {
 	} else if err != nil {
 		t.Fatal(err)
 	}
-	paths, err := parseCgroupFile("/proc/self/cgroup")
+	paths, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -63,7 +63,7 @@ func TestPidPath(t *testing.T) {
 	} else if err != nil {
 		t.Fatal(err)
 	}
-	paths, err := parseCgroupFile("/proc/self/cgroup")
+	paths, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/rdma.go b/rdma.go
index b6f0d416..3b59b107 100644
--- a/rdma.go
+++ b/rdma.go
@@ -67,6 +67,7 @@ func (p *rdmaController) Create(path string, resources *specs.LinuxResources) er
 
 	for device, limit := range resources.Rdma {
 		if device != "" && (limit.HcaHandles != nil || limit.HcaObjects != nil) {
+			limit := limit
 			return retryingWriteFile(
 				filepath.Join(p.Path(path), "rdma.max"),
 				[]byte(createCmdString(device, &limit)),
diff --git a/systemd.go b/systemd.go
index c17f34a6..4da57cb4 100644
--- a/systemd.go
+++ b/systemd.go
@@ -17,6 +17,7 @@
 package cgroups
 
 import (
+	"context"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -78,7 +79,8 @@ func (s *SystemdController) Name() Name {
 }
 
 func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
-	conn, err := systemdDbus.New()
+	ctx := context.TODO()
+	conn, err := systemdDbus.NewWithContext(ctx)
 	if err != nil {
 		return err
 	}
@@ -90,7 +92,7 @@ func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
 	checkDelegate := func() {
 		canDelegate = true
 		dlSlice := newProperty("Delegate", true)
-		if _, err := conn.StartTransientUnit(slice, "testdelegate", []systemdDbus.Property{dlSlice}, nil); err != nil {
+		if _, err := conn.StartTransientUnitContext(ctx, slice, "testdelegate", []systemdDbus.Property{dlSlice}, nil); err != nil {
 			if dbusError, ok := err.(dbus.Error); ok {
 				// Starting with systemd v237, Delegate is not even a property of slices anymore,
 				// so the D-Bus call fails with "InvalidArgs" error.
@@ -100,7 +102,7 @@ func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
 			}
 		}
 
-		conn.StopUnit(slice, "testDelegate", nil)
+		_, _ = conn.StopUnitContext(ctx, slice, "testDelegate", nil)
 	}
 	once.Do(checkDelegate)
 	properties := []systemdDbus.Property{
@@ -118,7 +120,7 @@ func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
 	}
 
 	ch := make(chan string)
-	_, err = conn.StartTransientUnit(name, "replace", properties, ch)
+	_, err = conn.StartTransientUnitContext(ctx, name, "replace", properties, ch)
 	if err != nil {
 		return err
 	}
@@ -127,14 +129,15 @@ func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
 }
 
 func (s *SystemdController) Delete(path string) error {
-	conn, err := systemdDbus.New()
+	ctx := context.TODO()
+	conn, err := systemdDbus.NewWithContext(ctx)
 	if err != nil {
 		return err
 	}
 	defer conn.Close()
 	_, name := splitName(path)
 	ch := make(chan string)
-	_, err = conn.StopUnit(name, "replace", ch)
+	_, err = conn.StopUnitContext(ctx, name, "replace", ch)
 	if err != nil {
 		return err
 	}
diff --git a/utils.go b/utils.go
index ed894b3e..2297980d 100644
--- a/utils.go
+++ b/utils.go
@@ -164,9 +164,9 @@ func remove(path string) error {
 	return fmt.Errorf("cgroups: unable to remove path %q", path)
 }
 
-// readPids will read all the pids of processes in a cgroup by the provided path
-func readPids(path string, subsystem Name) ([]Process, error) {
-	f, err := os.Open(filepath.Join(path, cgroupProcs))
+// readPids will read all the pids of processes or tasks in a cgroup by the provided path
+func readPids(path string, subsystem Name, pType procType) ([]Process, error) {
+	f, err := os.Open(filepath.Join(path, pType))
 	if err != nil {
 		return nil, err
 	}
@@ -195,36 +195,6 @@ func readPids(path string, subsystem Name) ([]Process, error) {
 	return out, nil
 }
 
-// readTasksPids will read all the pids of tasks in a cgroup by the provided path
-func readTasksPids(path string, subsystem Name) ([]Task, error) {
-	f, err := os.Open(filepath.Join(path, cgroupTasks))
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-	var (
-		out []Task
-		s   = bufio.NewScanner(f)
-	)
-	for s.Scan() {
-		if t := s.Text(); t != "" {
-			pid, err := strconv.Atoi(t)
-			if err != nil {
-				return nil, err
-			}
-			out = append(out, Task{
-				Pid:       pid,
-				Subsystem: subsystem,
-				Path:      path,
-			})
-		}
-	}
-	if err := s.Err(); err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
 func hugePageSizes() ([]string, error) {
 	var (
 		pageSizes []string
@@ -285,7 +255,16 @@ func parseKV(raw string) (string, uint64, error) {
 	}
 }
 
-func parseCgroupFile(path string) (map[string]string, error) {
+// ParseCgroupFile parses the given cgroup file, typically /proc/self/cgroup
+// or /proc/<pid>/cgroup, into a map of subsystems to cgroup paths, e.g.
+//   "cpu": "/user.slice/user-1000.slice"
+//   "pids": "/user.slice/user-1000.slice"
+// etc.
+//
+// Note that for cgroup v2 unified hierarchy, there are no per-controller
+// cgroup paths, so the resulting map will have a single element where the key
+// is empty string ("") and the value is the cgroup path the <pid> is in.
+func ParseCgroupFile(path string) (map[string]string, error) {
 	f, err := os.Open(path)
 	if err != nil {
 		return nil, err
diff --git a/v2/devicefilter.go b/v2/devicefilter.go
index 4b8c32be..0882036c 100644
--- a/v2/devicefilter.go
+++ b/v2/devicefilter.go
@@ -23,15 +23,16 @@
 //
 // This particular Go implementation based on runc version
 // https://github.com/opencontainers/runc/blob/master/libcontainer/cgroups/ebpf/devicefilter/devicefilter.go
+
 package v2
 
 import (
+	"errors"
 	"fmt"
 	"math"
 
 	"github.com/cilium/ebpf/asm"
 	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 )
 
@@ -106,13 +107,13 @@ func (p *program) appendDevice(dev specs.LinuxDeviceCgroup) error {
 		hasType = false
 	default:
 		// if not specified in OCI json, typ is set to DeviceTypeAll
-		return errors.Errorf("invalid DeviceType %q", dev.Type)
+		return fmt.Errorf("invalid DeviceType %q", dev.Type)
 	}
 	if *dev.Major > math.MaxUint32 {
-		return errors.Errorf("invalid major %d", *dev.Major)
+		return fmt.Errorf("invalid major %d", *dev.Major)
 	}
 	if *dev.Minor > math.MaxUint32 {
-		return errors.Errorf("invalid minor %d", *dev.Major)
+		return fmt.Errorf("invalid minor %d", *dev.Major)
 	}
 	hasMajor := *dev.Major >= 0 // if not specified in OCI json, major is set to -1
 	hasMinor := *dev.Minor >= 0
@@ -126,7 +127,7 @@ func (p *program) appendDevice(dev specs.LinuxDeviceCgroup) error {
 		case 'm':
 			bpfAccess |= unix.BPF_DEVCG_ACC_MKNOD
 		default:
-			return errors.Errorf("unknown device access %v", r)
+			return fmt.Errorf("unknown device access %v", r)
 		}
 	}
 	// If the access is rwm, skip the check.
diff --git a/v2/ebpf.go b/v2/ebpf.go
index bd384818..45bf5f99 100644
--- a/v2/ebpf.go
+++ b/v2/ebpf.go
@@ -17,11 +17,12 @@
 package v2
 
 import (
+	"fmt"
+
 	"github.com/cilium/ebpf"
 	"github.com/cilium/ebpf/asm"
 	"github.com/cilium/ebpf/link"
 	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 )
 
@@ -50,7 +51,7 @@ func LoadAttachCgroupDeviceFilter(insts asm.Instructions, license string, dirFD
 		Flags:   unix.BPF_F_ALLOW_MULTI,
 	})
 	if err != nil {
-		return nilCloser, errors.Wrap(err, "failed to call BPF_PROG_ATTACH (BPF_CGROUP_DEVICE, BPF_F_ALLOW_MULTI)")
+		return nilCloser, fmt.Errorf("failed to call BPF_PROG_ATTACH (BPF_CGROUP_DEVICE, BPF_F_ALLOW_MULTI): %w", err)
 	}
 	closer := func() error {
 		err = link.RawDetachProgram(link.RawDetachProgramOptions{
@@ -59,7 +60,7 @@ func LoadAttachCgroupDeviceFilter(insts asm.Instructions, license string, dirFD
 			Attach:  ebpf.AttachCGroupDevice,
 		})
 		if err != nil {
-			return errors.Wrap(err, "failed to call BPF_PROG_DETACH (BPF_CGROUP_DEVICE)")
+			return fmt.Errorf("failed to call BPF_PROG_DETACH (BPF_CGROUP_DEVICE): %w", err)
 		}
 		return nil
 	}
diff --git a/v2/errors.go b/v2/errors.go
index dfab548e..eeae362b 100644
--- a/v2/errors.go
+++ b/v2/errors.go
@@ -18,29 +18,9 @@ package v2
 
 import (
 	"errors"
-	"os"
 )
 
 var (
-	ErrInvalidPid               = errors.New("cgroups: pid must be greater than 0")
-	ErrMountPointNotExist       = errors.New("cgroups: cgroup mountpoint does not exist")
-	ErrInvalidFormat            = errors.New("cgroups: parsing file with invalid format failed")
-	ErrFreezerNotSupported      = errors.New("cgroups: freezer cgroup (v2) not supported on this system")
-	ErrMemoryNotSupported       = errors.New("cgroups: memory cgroup (v2) not supported on this system")
-	ErrPidsNotSupported         = errors.New("cgroups: pids cgroup (v2) not supported on this system")
-	ErrCPUNotSupported          = errors.New("cgroups: cpu cgroup (v2) not supported on this system")
-	ErrCgroupDeleted            = errors.New("cgroups: cgroup deleted")
-	ErrNoCgroupMountDestination = errors.New("cgroups: cannot find cgroup mount destination")
-	ErrInvalidGroupPath         = errors.New("cgroups: invalid group path")
+	ErrInvalidFormat    = errors.New("cgroups: parsing file with invalid format failed")
+	ErrInvalidGroupPath = errors.New("cgroups: invalid group path")
 )
-
-// ErrorHandler is a function that handles and acts on errors
-type ErrorHandler func(err error) error
-
-// IgnoreNotExist ignores any errors that are for not existing files
-func IgnoreNotExist(err error) error {
-	if os.IsNotExist(err) {
-		return nil
-	}
-	return err
-}
diff --git a/v2/manager.go b/v2/manager.go
index 3bb546cb..afed14c6 100644
--- a/v2/manager.go
+++ b/v2/manager.go
@@ -18,6 +18,9 @@ package v2
 
 import (
 	"bufio"
+	"context"
+	"errors"
+	"fmt"
 	"io/ioutil"
 	"math"
 	"os"
@@ -28,10 +31,10 @@ import (
 	"time"
 
 	"github.com/containerd/cgroups/v2/stats"
+
 	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
 	"github.com/godbus/dbus/v5"
 	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 )
@@ -270,7 +273,9 @@ func (c *Manager) ToggleControllers(controllers []string, t ControllerToggle) er
 			// When running as rootless, the user may face EPERM on parent groups, but it is neglible when the
 			// controller is already written.
 			// So we only return the last error.
-			lastErr = errors.Wrapf(err, "failed to write subtree controllers %+v to %q", controllers, filePath)
+			lastErr = fmt.Errorf("failed to write subtree controllers %+v to %q: %w", controllers, filePath, err)
+		} else {
+			lastErr = nil
 		}
 	}
 	return lastErr
@@ -300,15 +305,23 @@ func (c *Manager) NewChild(name string, resources *Resources) (*Manager, error)
 	if err := os.MkdirAll(path, defaultDirPerm); err != nil {
 		return nil, err
 	}
+	m := Manager{
+		unifiedMountpoint: c.unifiedMountpoint,
+		path:              path,
+	}
+	if resources != nil {
+		if err := m.ToggleControllers(resources.EnabledControllers(), Enable); err != nil {
+			// clean up cgroup dir on failure
+			os.Remove(path)
+			return nil, err
+		}
+	}
 	if err := setResources(path, resources); err != nil {
 		// clean up cgroup dir on failure
 		os.Remove(path)
 		return nil, err
 	}
-	return &Manager{
-		unifiedMountpoint: c.unifiedMountpoint,
-		path:              path,
-	}, nil
+	return &m, nil
 }
 
 func (c *Manager) AddProc(pid uint64) error {
@@ -515,7 +528,7 @@ func readKVStatsFile(path string, file string, out map[string]interface{}) error
 	for s.Scan() {
 		name, value, err := parseKV(s.Text())
 		if err != nil {
-			return errors.Wrapf(err, "error while parsing %s (line=%q)", filepath.Join(path, file), s.Text())
+			return fmt.Errorf("error while parsing %s (line=%q): %w", filepath.Join(path, file), s.Text(), err)
 		}
 		out[name] = value
 	}
@@ -547,17 +560,39 @@ func (c *Manager) freeze(path string, state State) error {
 	}
 }
 
+func (c *Manager) isCgroupEmpty() bool {
+	// In case of any error we return true so that we exit and don't leak resources
+	out := make(map[string]interface{})
+	if err := readKVStatsFile(c.path, "cgroup.events", out); err != nil {
+		return true
+	}
+	if v, ok := out["populated"]; ok {
+		populated, ok := v.(uint64)
+		if !ok {
+			return true
+		}
+		return populated == 0
+	}
+	return true
+}
+
 // MemoryEventFD returns inotify file descriptor and 'memory.events' inotify watch descriptor
 func (c *Manager) MemoryEventFD() (int, uint32, error) {
 	fpath := filepath.Join(c.path, "memory.events")
 	fd, err := syscall.InotifyInit()
 	if err != nil {
-		return 0, 0, errors.Errorf("Failed to create inotify fd")
+		return 0, 0, errors.New("failed to create inotify fd")
 	}
 	wd, err := syscall.InotifyAddWatch(fd, fpath, unix.IN_MODIFY)
-	if wd < 0 {
+	if err != nil {
+		syscall.Close(fd)
+		return 0, 0, fmt.Errorf("failed to add inotify watch for %q: %w", fpath, err)
+	}
+	// monitor to detect process exit/cgroup deletion
+	evpath := filepath.Join(c.path, "cgroup.events")
+	if _, err = syscall.InotifyAddWatch(fd, evpath, unix.IN_MODIFY); err != nil {
 		syscall.Close(fd)
-		return 0, 0, errors.Errorf("Failed to add inotify watch for %q", fpath)
+		return 0, 0, fmt.Errorf("failed to add inotify watch for %q: %w", evpath, err)
 	}
 
 	return fd, uint32(wd), nil
@@ -565,22 +600,56 @@ func (c *Manager) MemoryEventFD() (int, uint32, error) {
 
 func (c *Manager) EventChan() (<-chan Event, <-chan error) {
 	ec := make(chan Event)
-	errCh := make(chan error)
+	errCh := make(chan error, 1)
 	go c.waitForEvents(ec, errCh)
 
-	return ec, nil
+	return ec, errCh
 }
 
-func (c *Manager) waitForEvents(ec chan<- Event, errCh chan<- error) {
-	fd, wd, err := c.MemoryEventFD()
+func parseMemoryEvents(out map[string]interface{}) (Event, error) {
+	e := Event{}
+	if v, ok := out["high"]; ok {
+		e.High, ok = v.(uint64)
+		if !ok {
+			return Event{}, fmt.Errorf("cannot convert high to uint64: %+v", v)
+		}
+	}
+	if v, ok := out["low"]; ok {
+		e.Low, ok = v.(uint64)
+		if !ok {
+			return Event{}, fmt.Errorf("cannot convert low to uint64: %+v", v)
+		}
+	}
+	if v, ok := out["max"]; ok {
+		e.Max, ok = v.(uint64)
+		if !ok {
+			return Event{}, fmt.Errorf("cannot convert max to uint64: %+v", v)
+		}
+	}
+	if v, ok := out["oom"]; ok {
+		e.OOM, ok = v.(uint64)
+		if !ok {
+			return Event{}, fmt.Errorf("cannot convert oom to uint64: %+v", v)
+		}
+	}
+	if v, ok := out["oom_kill"]; ok {
+		e.OOMKill, ok = v.(uint64)
+		if !ok {
+			return Event{}, fmt.Errorf("cannot convert oom_kill to uint64: %+v", v)
+		}
+	}
+	return e, nil
+}
 
-	defer syscall.InotifyRmWatch(fd, wd)
-	defer syscall.Close(fd)
+func (c *Manager) waitForEvents(ec chan<- Event, errCh chan<- error) {
+	defer close(errCh)
 
+	fd, _, err := c.MemoryEventFD()
 	if err != nil {
 		errCh <- err
 		return
 	}
+	defer syscall.Close(fd)
 
 	for {
 		buffer := make([]byte, syscall.SizeofInotifyEvent*10)
@@ -591,48 +660,22 @@ func (c *Manager) waitForEvents(ec chan<- Event, errCh chan<- error) {
 		}
 		if bytesRead >= syscall.SizeofInotifyEvent {
 			out := make(map[string]interface{})
-			if err := readKVStatsFile(c.path, "memory.events", out); err == nil {
-				e := Event{}
-				if v, ok := out["high"]; ok {
-					e.High, ok = v.(uint64)
-					if !ok {
-						errCh <- errors.Errorf("cannot convert high to uint64: %+v", v)
-						return
-					}
-				}
-				if v, ok := out["low"]; ok {
-					e.Low, ok = v.(uint64)
-					if !ok {
-						errCh <- errors.Errorf("cannot convert low to uint64: %+v", v)
-						return
-					}
-				}
-				if v, ok := out["max"]; ok {
-					e.Max, ok = v.(uint64)
-					if !ok {
-						errCh <- errors.Errorf("cannot convert max to uint64: %+v", v)
-						return
-					}
-				}
-				if v, ok := out["oom"]; ok {
-					e.OOM, ok = v.(uint64)
-					if !ok {
-						errCh <- errors.Errorf("cannot convert oom to uint64: %+v", v)
-						return
-					}
+			if err := readKVStatsFile(c.path, "memory.events", out); err != nil {
+				// When cgroup is deleted read may return -ENODEV instead of -ENOENT from open.
+				if _, statErr := os.Lstat(filepath.Join(c.path, "memory.events")); !os.IsNotExist(statErr) {
+					errCh <- err
 				}
-				if v, ok := out["oom_kill"]; ok {
-					e.OOMKill, ok = v.(uint64)
-					if !ok {
-						errCh <- errors.Errorf("cannot convert oom_kill to uint64: %+v", v)
-						return
-					}
-				}
-				ec <- e
-			} else {
+				return
+			}
+			e, err := parseMemoryEvents(out)
+			if err != nil {
 				errCh <- err
 				return
 			}
+			ec <- e
+			if c.isCgroupEmpty() {
+				return
+			}
 		}
 	}
 }
@@ -645,9 +688,9 @@ func setDevices(path string, devices []specs.LinuxDeviceCgroup) error {
 	if err != nil {
 		return err
 	}
-	dirFD, err := unix.Open(path, unix.O_DIRECTORY|unix.O_RDONLY, 0600)
+	dirFD, err := unix.Open(path, unix.O_DIRECTORY|unix.O_RDONLY|unix.O_CLOEXEC, 0600)
 	if err != nil {
-		return errors.Errorf("cannot get dir FD for %s", path)
+		return fmt.Errorf("cannot get dir FD for %s", path)
 	}
 	defer unix.Close(dirFD)
 	if _, err := LoadAttachCgroupDeviceFilter(insts, license, dirFD); err != nil {
@@ -662,8 +705,9 @@ func NewSystemd(slice, group string, pid int, resources *Resources) (*Manager, e
 	if slice == "" {
 		slice = defaultSlice
 	}
+	ctx := context.TODO()
 	path := filepath.Join(defaultCgroup2Path, slice, group)
-	conn, err := systemdDbus.New()
+	conn, err := systemdDbus.NewWithContext(ctx)
 	if err != nil {
 		return &Manager{}, err
 	}
@@ -733,7 +777,7 @@ func NewSystemd(slice, group string, pid int, resources *Resources) (*Manager, e
 	}
 
 	statusChan := make(chan string, 1)
-	if _, err := conn.StartTransientUnit(group, "replace", properties, statusChan); err == nil {
+	if _, err := conn.StartTransientUnitContext(ctx, group, "replace", properties, statusChan); err == nil {
 		select {
 		case <-statusChan:
 		case <-time.After(time.Second):
@@ -759,14 +803,15 @@ func LoadSystemd(slice, group string) (*Manager, error) {
 }
 
 func (c *Manager) DeleteSystemd() error {
-	conn, err := systemdDbus.New()
+	ctx := context.TODO()
+	conn, err := systemdDbus.NewWithContext(ctx)
 	if err != nil {
 		return err
 	}
 	defer conn.Close()
 	group := systemdUnitFromPath(c.path)
 	ch := make(chan string)
-	_, err = conn.StopUnit(group, "replace", ch)
+	_, err = conn.StopUnitContext(ctx, group, "replace", ch)
 	if err != nil {
 		return err
 	}
diff --git a/v2/manager_test.go b/v2/manager_test.go
new file mode 100644
index 00000000..35d104ca
--- /dev/null
+++ b/v2/manager_test.go
@@ -0,0 +1,76 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package v2
+
+import (
+	"fmt"
+	"os/exec"
+	"testing"
+	"time"
+
+	"go.uber.org/goleak"
+)
+
+func TestEventChanCleanupOnCgroupRemoval(t *testing.T) {
+	checkCgroupMode(t)
+
+	cmd := exec.Command("cat")
+	stdin, err := cmd.StdinPipe()
+	if err != nil {
+		t.Fatalf("Failed to create cat process: %v", err)
+	}
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("Failed to start cat process: %v", err)
+	}
+	proc := cmd.Process
+	if proc == nil {
+		t.Fatal("Process is nil")
+	}
+
+	group := fmt.Sprintf("testing-watcher-%d.scope", proc.Pid)
+	c, err := NewSystemd("", group, proc.Pid, &Resources{})
+	if err != nil {
+		t.Fatalf("Failed to init new cgroup manager: %v", err)
+	}
+
+	evCh, errCh := c.EventChan()
+
+	// give event goroutine a chance to start
+	time.Sleep(500 * time.Millisecond)
+
+	if err := stdin.Close(); err != nil {
+		t.Fatalf("Failed closing stdin: %v", err)
+	}
+	if err := cmd.Wait(); err != nil {
+		t.Fatalf("Failed waiting for cmd: %v", err)
+	}
+
+	done := false
+	for !done {
+		select {
+		case <-evCh:
+		case err := <-errCh:
+			if err != nil {
+				t.Fatalf("Unexpected error on error channel: %v", err)
+			}
+			done = true
+		case <-time.After(5 * time.Second):
+			t.Fatal("Timed out")
+		}
+	}
+	goleak.VerifyNone(t)
+}
diff --git a/v2/utils.go b/v2/utils.go
index 8b8d654d..902466f5 100644
--- a/v2/utils.go
+++ b/v2/utils.go
@@ -29,9 +29,9 @@ import (
 	"time"
 
 	"github.com/containerd/cgroups/v2/stats"
+
 	"github.com/godbus/dbus/v5"
 	"github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -61,7 +61,7 @@ func remove(path string) error {
 			return nil
 		}
 	}
-	return errors.Wrapf(err, "cgroups: unable to remove path %q", path)
+	return fmt.Errorf("cgroups: unable to remove path %q: %w", path, err)
 }
 
 // parseCgroupProcsFile parses /sys/fs/cgroup/$GROUPPATH/cgroup.procs