kill all processes in a container in the event of OOM

Set memory.oom.group if using cgroups v2 unified mode so all processes in
the container will be killed together in the event of an OOM kill.

pkg/kubelet/kuberuntime/kuberuntime_container_linux.go

@@ -215,6 +215,15 @@ func (m *kubeGenericRuntimeManager) calculateLinuxResources(cpuRequest, cpuLimit
 		resources.CpuPeriod = cpuPeriod
 	}
 
+	// runc requires cgroupv2 for unified mode
+	if libcontainercgroups.IsCgroup2UnifiedMode() {
+		resources.Unified = map[string]string{
+			// Ask the kernel to kill all processes in the container cgroup in case of OOM.
+			// See memory.oom.group in https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html for
+			// more info.
+			"memory.oom.group": "1",
+		}
+	}
 	return &resources
 }
 

test/e2e_node/oomkiller_linux_test.go

@@ -19,7 +19,6 @@ package e2enode
 import (
 	"context"
 	"fmt"
-	"time"
 
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -29,35 +28,52 @@ import (
 	admissionapi "k8s.io/pod-security-admission/api"
 
 	"github.com/onsi/ginkgo/v2"
+	libcontainercgroups "github.com/opencontainers/runc/libcontainer/cgroups"
 )
 
 type testCase struct {
+	name                   string
 	podSpec                *v1.Pod
 	oomTargetContainerName string
 }
 
-const PodOOMKilledTimeout = 2 * time.Minute
-
 var _ = SIGDescribe("OOMKiller [LinuxOnly] [NodeConformance]", func() {
 	f := framework.NewDefaultFramework("oomkiller-test")
 	f.NamespacePodSecurityEnforceLevel = admissionapi.LevelPrivileged
 
-	containerName := "oomkill-target-container"
-	oomPodSpec := getOOMTargetPod("oomkill-target-pod", containerName)
-	runOomKillerTest(f, testCase{podSpec: oomPodSpec, oomTargetContainerName: containerName})
+	testCases := []testCase{{
+		name:                   "single process container",
+		oomTargetContainerName: "oomkill-single-target-container",
+		podSpec: getOOMTargetPod("oomkill-target-pod", "oomkill-single-target-container",
+			getOOMTargetContainer),
+	}}
+
+	// If using cgroup v2, we set memory.oom.group=1 for the container cgroup so that any process which gets OOM killed
+	// in the process, causes all processes in the container to get OOM killed
+	if libcontainercgroups.IsCgroup2UnifiedMode() {
+		testCases = append(testCases, testCase{
+			name:                   "multi process container",
+			oomTargetContainerName: "oomkill-multi-target-container",
+			podSpec: getOOMTargetPod("oomkill-target-pod", "oomkill-multi-target-container",
+				getOOMTargetContainerMultiProcess),
+		})
+	}
+	for _, tc := range testCases {
+		runOomKillerTest(f, tc)
+	}
 })
 
 func runOomKillerTest(f *framework.Framework, testCase testCase) {
-	ginkgo.Context("", func() {
+	ginkgo.Context(testCase.name, func() {
 		ginkgo.BeforeEach(func() {
 			ginkgo.By("setting up the pod to be used in the test")
 			e2epod.NewPodClient(f).Create(context.TODO(), testCase.podSpec)
 		})
 
 		ginkgo.It("The containers terminated by OOM killer should have the reason set to OOMKilled", func() {
-
 			ginkgo.By("Waiting for the pod to be failed")
-			e2epod.WaitForPodTerminatedInNamespace(context.TODO(), f.ClientSet, testCase.podSpec.Name, "", f.Namespace.Name)
+			err := e2epod.WaitForPodTerminatedInNamespace(context.TODO(), f.ClientSet, testCase.podSpec.Name, "", f.Namespace.Name)
+			framework.ExpectNoError(err, "Failed waiting for pod to terminate, %s/%s", f.Namespace.Name, testCase.podSpec.Name)
 
 			ginkgo.By("Fetching the latest pod status")
 			pod, err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).Get(context.TODO(), testCase.podSpec.Name, metav1.GetOptions{})
@@ -88,7 +104,7 @@ func verifyReasonForOOMKilledContainer(pod *v1.Pod, oomTargetContainerName strin
 		fmt.Sprintf("pod: %q, container: %q has unexpected reason: %q", pod.Name, container.Name, container.State.Terminated.Reason))
 }
 
-func getOOMTargetPod(podName string, ctnName string) *v1.Pod {
+func getOOMTargetPod(podName string, ctnName string, createContainer func(name string) v1.Container) *v1.Pod {
 	return &v1.Pod{
 		ObjectMeta: metav1.ObjectMeta{
 			Name: podName,
@@ -96,12 +112,14 @@ func getOOMTargetPod(podName string, ctnName string) *v1.Pod {
 		Spec: v1.PodSpec{
 			RestartPolicy: v1.RestartPolicyNever,
 			Containers: []v1.Container{
-				getOOMTargetContainer(ctnName),
+				createContainer(ctnName),
 			},
 		},
 	}
 }
 
+// getOOMTargetContainer returns a container with a single process, which attempts to allocate more memory than is
+// allowed by the container memory limit.
 func getOOMTargetContainer(name string) v1.Container {
 	return v1.Container{
 		Name:  name,
@@ -122,3 +140,26 @@ func getOOMTargetContainer(name string) v1.Container {
 		},
 	}
 }
+
+// getOOMTargetContainerMultiProcess returns a container with two processes, one of which attempts to allocate more
+// memory than is allowed by the container memory limit, and a second process which just sleeps.
+func getOOMTargetContainerMultiProcess(name string) v1.Container {
+	return v1.Container{
+		Name:  name,
+		Image: busyboxImage,
+		Command: []string{
+			"sh",
+			"-c",
+			// use the dd tool to attempt to allocate 20M in a block which exceeds the limit
+			"dd if=/dev/zero of=/dev/null bs=20M & sleep 86400",
+		},
+		Resources: v1.ResourceRequirements{
+			Requests: v1.ResourceList{
+				v1.ResourceMemory: resource.MustParse("15Mi"),
+			},
+			Limits: v1.ResourceList{
+				v1.ResourceMemory: resource.MustParse("15Mi"),
+			},
+		},
+	}
+}