Ensure panic_on_oom disabled

pkg/kubelet/container_manager_linux.go

@@ -142,26 +142,48 @@ func createManager(containerName string) *fs.Manager {
 	}
 }
 
-const sysctlVmOvercommitMemory = "vm/overcommit_memory"
+// TODO: plumb this up as a flag to Kubelet in a future PR
+type KernelTunableBehavior string
 
-// disableKernelMemoryOvercommitHandling tells the kernel to perform no memory over-commit handling.
-// Under this setting, the potential for memory overload is increased, but so is performance for
-// memory-intensive tasks
-// sets /proc/sys/vm/overcommit_memory to 1
-func disableKernelMemoryOvercommitHandling() error {
-	val, err := utilsysctl.GetSysctl(sysctlVmOvercommitMemory)
-	if err != nil {
-		return err
+const (
+	KernelTunableWarn   KernelTunableBehavior = "warn"
+	KernelTunableError  KernelTunableBehavior = "error"
+	KernelTunableModify KernelTunableBehavior = "modify"
+)
+
+// setupKernelTunables validates kernel tunable flags are set as expected
+// depending upon the specified option, it will either warn, error, or modify the kernel tunable flags
+func setupKernelTunables(option KernelTunableBehavior) error {
+	desiredState := map[string]int{
+		utilsysctl.VmOvercommitMemory: utilsysctl.VmOvercommitMemoryAlways,
+		utilsysctl.VmPanicOnOOM:       utilsysctl.VmPanicOnOOMInvokeOOMKiller,
 	}
-	if val == 1 {
-		return nil
+
+	errList := []error{}
+	for flag, expectedValue := range desiredState {
+		val, err := utilsysctl.GetSysctl(flag)
+		if err != nil {
+			errList = append(errList, err)
+			continue
+		}
+		if val == expectedValue {
+			continue
+		}
+
+		switch option {
+		case KernelTunableError:
+			errList = append(errList, fmt.Errorf("Invalid kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val))
+		case KernelTunableWarn:
+			glog.V(2).Infof("Invalid kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val)
+		case KernelTunableModify:
+			glog.V(2).Infof("Updating kernel flag: %v, expected value: %v, actual value: %v", flag, expectedValue, val)
+			err = utilsysctl.SetSysctl(flag, expectedValue)
+			if err != nil {
+				errList = append(errList, err)
+			}
+		}
 	}
-	glog.V(2).Infof("Updating kernel memory overcommit flag from %v to %v", val, 1)
-	err = utilsysctl.SetSysctl(sysctlVmOvercommitMemory, 1)
-	if err != nil {
-		return err
-	}
-	return nil
+	return errors.NewAggregate(errList)
 }
 
 func (cm *containerManagerImpl) setupNode() error {
@@ -169,7 +191,8 @@ func (cm *containerManagerImpl) setupNode() error {
 		return err
 	}
 
-	if err := disableKernelMemoryOvercommitHandling(); err != nil {
+	// TODO: plumb kernel tunable options into container manager, right now, we modify by default
+	if err := setupKernelTunables(KernelTunableModify); err != nil {
 		return err
 	}
 

pkg/util/sysctl/sysctl.go

@@ -23,7 +23,14 @@ import (
 	"strings"
 )
 
-const sysctlBase = "/proc/sys"
+const (
+	sysctlBase         = "/proc/sys"
+	VmOvercommitMemory = "vm/overcommit_memory"
+	VmPanicOnOOM       = "vm/panic_on_oom"
+
+	VmOvercommitMemoryAlways    = 1 // kernel performs no memory over-commit handling
+	VmPanicOnOOMInvokeOOMKiller = 0 // kernel calls the oom_killer function when OOM occurs
+)
 
 // GetSysctl returns the value for the specified sysctl setting
 func GetSysctl(sysctl string) (int, error) {