fix runc events error in cgroup v2

Signed-off-by: lifubang <lifubang@acmcoder.com>

libcontainer/container_linux.go

@@ -648,6 +648,13 @@ func (c *linuxContainer) NotifyOOM() (<-chan struct{}, error) {
 	if c.config.RootlessCgroups {
 		logrus.Warn("getting OOM notifications may fail if you don't have the full access to cgroups")
 	}
+	if cgroups.IsCgroup2UnifiedMode() {
+		path, err := c.cgroupManager.GetUnifiedPath()
+		if err != nil {
+			return nil, err
+		}
+		return notifyOnOOMV2(path)
+	}
 	return notifyOnOOM(c.cgroupManager.GetPaths())
 }
 

libcontainer/notify_linux_v2.go

@@ -0,0 +1,102 @@
+// +build linux
+
+package libcontainer
+
+import (
+	"io/ioutil"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"unsafe"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+func getValueFromCgroup(path, key string) (int, error) {
+	content, err := ioutil.ReadFile(path)
+	if err != nil {
+		return 0, err
+	}
+
+	lines := strings.Split(string(content), "\n")
+	for _, line := range lines {
+		arr := strings.Split(line, " ")
+		if len(arr) == 2 && arr[0] == key {
+			return strconv.Atoi(arr[1])
+		}
+	}
+	return 0, nil
+}
+
+func registerMemoryEventV2(cgDir, evName, cgEvName string) (<-chan struct{}, error) {
+	eventControlPath := filepath.Join(cgDir, evName)
+	cgEvPath := filepath.Join(cgDir, cgEvName)
+	fd, err := unix.InotifyInit()
+	if err != nil {
+		return nil, errors.Wrap(err, "unable to init inotify")
+	}
+	// watching oom kill
+	evFd, err := unix.InotifyAddWatch(fd, eventControlPath, unix.IN_MODIFY)
+	if err != nil {
+		unix.Close(fd)
+		return nil, errors.Wrap(err, "unable to add inotify watch")
+	}
+	// Because no `unix.IN_DELETE|unix.IN_DELETE_SELF` event for cgroup file system, so watching all process exited
+	cgFd, err := unix.InotifyAddWatch(fd, cgEvPath, unix.IN_MODIFY)
+	if err != nil {
+		unix.Close(fd)
+		return nil, errors.Wrap(err, "unable to add inotify watch")
+	}
+	ch := make(chan struct{})
+	go func() {
+		var (
+			buffer [unix.SizeofInotifyEvent + unix.PathMax + 1]byte
+			offset uint32
+		)
+		defer func() {
+			unix.Close(fd)
+			close(ch)
+		}()
+
+		for {
+			n, err := unix.Read(fd, buffer[:])
+			if err != nil {
+				logrus.Warnf("unable to read event data from inotify, got error: %v", err)
+				return
+			}
+			if n < unix.SizeofInotifyEvent {
+				logrus.Warnf("we should read at least %d bytes from inotify, but got %d bytes.", unix.SizeofInotifyEvent, n)
+				return
+			}
+			offset = 0
+			for offset <= uint32(n-unix.SizeofInotifyEvent) {
+				rawEvent := (*unix.InotifyEvent)(unsafe.Pointer(&buffer[offset]))
+				offset += unix.SizeofInotifyEvent + uint32(rawEvent.Len)
+				if rawEvent.Mask&unix.IN_MODIFY != unix.IN_MODIFY {
+					continue
+				}
+				switch int(rawEvent.Wd) {
+				case evFd:
+					oom, err := getValueFromCgroup(eventControlPath, "oom_kill")
+					if err != nil || oom > 0 {
+						ch <- struct{}{}
+					}
+				case cgFd:
+					pids, err := getValueFromCgroup(cgEvPath, "populated")
+					if err != nil || pids == 0 {
+						return
+					}
+				}
+			}
+		}
+	}()
+	return ch, nil
+}
+
+// notifyOnOOMV2 returns channel on which you can expect event about OOM,
+// if process died without OOM this channel will be closed.
+func notifyOnOOMV2(path string) (<-chan struct{}, error) {
+	return registerMemoryEventV2(path, "memory.events", "cgroup.events")
+}

tests/integration/events.bats

@@ -13,8 +13,8 @@ function teardown() {
 
 @test "events --stats" {
   # XXX: currently cgroups require root containers.
-  # TODO: support cgroup v2 memory.events
-  requires root cgroups_v1
+  requires root
+  init_cgroup_paths
 
   # run busybox detached
   runc run -d --console-socket $CONSOLE_SOCKET test_busybox
@@ -27,10 +27,10 @@ function teardown() {
   [[ "${lines[0]}" == *"data"* ]]
 }
 
-@test "events --interval default " {
+@test "events --interval default" {
   # XXX: currently cgroups require root containers.
-  # TODO: support cgroup v2 memory.events
-  requires root cgroups_v1
+  requires root
+  init_cgroup_paths
 
   # run busybox detached
   runc run -d --console-socket $CONSOLE_SOCKET test_busybox
@@ -55,10 +55,10 @@ function teardown() {
   [[ "${lines[0]}" == *"data"* ]]
 }
 
-@test "events --interval 1s " {
+@test "events --interval 1s" {
   # XXX: currently cgroups require root containers.
-  # TODO: support cgroup v2 memory.events
-  requires root cgroups_v1
+  requires root
+  init_cgroup_paths
 
   # run busybox detached
   runc run -d --console-socket $CONSOLE_SOCKET test_busybox
@@ -82,10 +82,10 @@ function teardown() {
   [ "$status" -eq 0 ]
 }
 
-@test "events --interval 100ms " {
+@test "events --interval 100ms" {
   # XXX: currently cgroups require root containers.
-  # TODO: support cgroup v2 memory.events
-  requires root cgroups_v1
+  requires root
+  init_cgroup_paths
 
   # run busybox detached
   runc run -d --console-socket $CONSOLE_SOCKET test_busybox
@@ -111,3 +111,40 @@ function teardown() {
   run eval "grep -q 'test_busybox' events.log"
   [ "$status" -eq 0 ]
 }
+
+@test "events oom " {
+  # XXX: currently cgroups require root containers.
+  requires root
+  init_cgroup_paths
+  
+  # we need the container to hit OOM, so disable swap
+  # ("swap" here is actually memory+swap)
+  DATA=$(cat <<EOF
+  "memory": {
+    "limit": 33554432,
+    "swap": 33554432
+  },
+EOF
+  )
+  DATA=$(echo ${DATA} | sed 's/\n/\\n/g')
+  sed -i "s/\(\"resources\": {\)/\1\n${DATA}/" ${BUSYBOX_BUNDLE}/config.json
+
+  # run busybox detached
+  runc run -d --console-socket $CONSOLE_SOCKET test_busybox
+  [ "$status" -eq 0 ]
+
+  # spawn two sub processes (shells)
+  # the first sub process is an event logger that sends stats events to events.log
+  # the second sub process exec a memory hog process to cause a oom condition
+  # and waits for an oom event
+  (__runc events test_busybox > events.log) &
+  (
+    retry 10 1 eval "grep -q 'test_busybox' events.log"
+    __runc exec -d test_busybox sh -c 'test=$(dd if=/dev/urandom ibs=5120k)'
+    retry 10 1 eval "grep -q 'oom' events.log"
+    __runc delete -f test_busybox
+  ) &
+  wait # wait for the above sub shells to finish
+
+  grep -q '{"type":"oom","id":"test_busybox"}' events.log
+}