vm/gce: allow non-preemptible VMs

We are seeing some flakes during bisection and image testing.
Hard to tell what's the root cause because they are episodic.
But using non-preemptible VMs for bisection and image testing
looks good on all fronts.

Update #501

pkg/gce/gce.go

@@ -92,7 +92,7 @@ func NewContext() (*Context, error) {
 	return ctx, nil
 }
 
-func (ctx *Context) CreateInstance(name, machineType, image, sshkey string) (string, error) {
+func (ctx *Context) CreateInstance(name, machineType, image, sshkey string, preemptible bool) (string, error) {
 	prefix := "https://www.googleapis.com/compute/v1/projects/" + ctx.ProjectID
 	sshkeyAttr := "syzkaller:" + sshkey
 	oneAttr := "1"
@@ -132,7 +132,7 @@ func (ctx *Context) CreateInstance(name, machineType, image, sshkey string) (str
 		},
 		Scheduling: &compute.Scheduling{
 			AutomaticRestart:  &falseAttr,
-			Preemptible:       true,
+			Preemptible:       preemptible,
 			OnHostMaintenance: "TERMINATE",
 		},
 	}

pkg/instance/instance.go

@@ -90,42 +90,36 @@ func (env *Env) BuildKernel(compilerBin, userspaceDir, cmdlineFile, sysctlFile s
 		cmdlineFile, sysctlFile, kernelConfig); err != nil {
 		return err
 	}
-	return SetConfigImage(cfg, imageDir)
+	return SetConfigImage(cfg, imageDir, true)
 }
 
-func SetConfigImage(cfg *mgrconfig.Config, imageDir string) error {
+func SetConfigImage(cfg *mgrconfig.Config, imageDir string, reliable bool) error {
 	cfg.KernelObj = filepath.Join(imageDir, "obj")
 	cfg.Image = filepath.Join(imageDir, "image")
 	if keyFile := filepath.Join(imageDir, "key"); osutil.IsExist(keyFile) {
 		cfg.SSHKey = keyFile
 	}
-	if cfg.Type == "qemu" || cfg.Type == "vmm" {
-		kernel := filepath.Join(imageDir, "kernel")
-		if !osutil.IsExist(kernel) {
-			kernel = ""
-		}
-		initrd := filepath.Join(imageDir, "initrd")
-		if !osutil.IsExist(initrd) {
-			initrd = ""
-		}
-		if kernel != "" || initrd != "" {
 	vmConfig := make(map[string]interface{})
 	if err := json.Unmarshal(cfg.VM, &vmConfig); err != nil {
 		return fmt.Errorf("failed to parse VM config: %v", err)
 	}
-			if kernel != "" {
+	if cfg.Type == "qemu" || cfg.Type == "vmm" {
+		if kernel := filepath.Join(imageDir, "kernel"); osutil.IsExist(kernel) {
 			vmConfig["kernel"] = kernel
 		}
-			if initrd != "" {
+		if initrd := filepath.Join(imageDir, "initrd"); osutil.IsExist(initrd) {
 			vmConfig["initrd"] = initrd
 		}
+	}
+	if cfg.Type == "gce" {
+		// Don't use preemptible VMs for image testing, patch testing and bisection.
+		vmConfig["preemptible"] = !reliable
+	}
 	vmCfg, err := json.Marshal(vmConfig)
 	if err != nil {
 		return fmt.Errorf("failed to serialize VM config: %v", err)
 	}
 	cfg.VM = vmCfg
-		}
-	}
 	return nil
 }
 

syz-ci/manager.go

@@ -435,7 +435,7 @@ func (mgr *Manager) createTestConfig(imageDir string, info *BuildInfo) (*mgrconf
 	mgrcfg.Name += "-test"
 	mgrcfg.Tag = info.KernelCommit
 	mgrcfg.Workdir = filepath.Join(imageDir, "workdir")
-	if err := instance.SetConfigImage(mgrcfg, imageDir); err != nil {
+	if err := instance.SetConfigImage(mgrcfg, imageDir, true); err != nil {
 		return nil, err
 	}
 	mgrcfg.KernelSrc = mgr.kernelDir
@@ -461,7 +461,7 @@ func (mgr *Manager) writeConfig(buildTag string) (string, error) {
 	}
 	mgrcfg.Tag = buildTag
 	mgrcfg.Workdir = mgr.workDir
-	if err := instance.SetConfigImage(mgrcfg, mgr.currentDir); err != nil {
+	if err := instance.SetConfigImage(mgrcfg, mgr.currentDir, false); err != nil {
 		return "", err
 	}
 	// Strictly saying this is somewhat racy as builder can concurrently

vm/gce/gce.go

@@ -39,7 +39,8 @@ type Config struct {
 	Count       int    `json:"count"`        // number of VMs to use
 	MachineType string `json:"machine_type"` // GCE machine type (e.g. "n1-highcpu-2")
 	GCSPath     string `json:"gcs_path"`     // GCS path to upload image
-	GCEImage    string `json:"gce_image"`    // Pre-created GCE image to use
+	GCEImage    string `json:"gce_image"`    // pre-created GCE image to use
+	Preemptible bool   `json:"preemptible"`  // use preemptible VMs if available (defaults to true)
 }
 
 type Pool struct {
@@ -68,6 +69,7 @@ func ctor(env *vmimpl.Env) (vmimpl.Pool, error) {
 	}
 	cfg := &Config{
 		Count:       1,
+		Preemptible: true,
 	}
 	if err := config.LoadData(env.Config, cfg); err != nil {
 		return nil, fmt.Errorf("failed to parse gce vm config: %v", err)
@@ -144,7 +146,8 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 		return nil, err
 	}
 	log.Logf(0, "creating instance: %v", name)
-	ip, err := pool.GCE.CreateInstance(name, pool.cfg.MachineType, pool.cfg.GCEImage, string(gceKeyPub))
+	ip, err := pool.GCE.CreateInstance(name, pool.cfg.MachineType, pool.cfg.GCEImage,
+		string(gceKeyPub), pool.cfg.Preemptible)
 	if err != nil {
 		return nil, err
 	}