diff --git a/cmd/kubeadm/app/cmd/phases/upgrade/apply/addons.go b/cmd/kubeadm/app/cmd/phases/upgrade/apply/addons.go
index fe3305b0f76..cbd1c02a099 100644
--- a/cmd/kubeadm/app/cmd/phases/upgrade/apply/addons.go
+++ b/cmd/kubeadm/app/cmd/phases/upgrade/apply/addons.go
@@ -106,7 +106,7 @@ func runCoreDNSAddon(c workflow.RunData) error {
 	return nil
 }
 
-// runKubeProxyAddon upgrades the KubeProxy addon.
+// runKubeProxyAddon upgrades the kube-proxy addon.
 func runKubeProxyAddon(c workflow.RunData) error {
 	cfg, client, _, out, dryRun, err := getInitData(c)
 	if err != nil {
diff --git a/cmd/kubeadm/app/cmd/phases/upgrade/apply/kubeletconfig.go b/cmd/kubeadm/app/cmd/phases/upgrade/apply/kubeletconfig.go
index a5b2d7490a9..2996b8af167 100644
--- a/cmd/kubeadm/app/cmd/phases/upgrade/apply/kubeletconfig.go
+++ b/cmd/kubeadm/app/cmd/phases/upgrade/apply/kubeletconfig.go
@@ -30,7 +30,7 @@ import (
 
 var (
 	kubeletConfigLongDesc = cmdutil.LongDesc(`
-		Download the kubelet configuration from the kubelet-config ConfigMap stored in the cluster
+		Upgrade the kubelet configuration for this node by downloading it from the kubelet-config ConfigMap stored in the cluster
 		`)
 )
 
diff --git a/cmd/kubeadm/app/cmd/phases/upgrade/apply/postupgrade.go b/cmd/kubeadm/app/cmd/phases/upgrade/apply/postupgrade.go
index 0ab43fa2926..8e4483d1025 100644
--- a/cmd/kubeadm/app/cmd/phases/upgrade/apply/postupgrade.go
+++ b/cmd/kubeadm/app/cmd/phases/upgrade/apply/postupgrade.go
@@ -28,7 +28,7 @@ import (
 func NewPostUpgradePhase() workflow.Phase {
 	return workflow.Phase{
 		Name:  "post-upgrade",
-		Short: "Run the post upgrade tasks",
+		Short: "Run post upgrade tasks",
 		Run:   runPostUpgrade,
 		InheritFlags: []string{
 			options.CfgPath,
@@ -43,7 +43,7 @@ func runPostUpgrade(c workflow.RunData) error {
 	if !ok {
 		return errors.New("preflight phase invoked with an invalid data struct")
 	}
-	// TODO: add the post upgrade tasks here when needed
+	// PLACEHOLDER: this phase should contain any release specific post-upgrade tasks.
 
 	return nil
 }
diff --git a/cmd/kubeadm/app/cmd/phases/upgrade/apply/preflight.go b/cmd/kubeadm/app/cmd/phases/upgrade/apply/preflight.go
index 7c97d8bba3e..259c6f6c3d5 100644
--- a/cmd/kubeadm/app/cmd/phases/upgrade/apply/preflight.go
+++ b/cmd/kubeadm/app/cmd/phases/upgrade/apply/preflight.go
@@ -68,30 +68,30 @@ func runPreflight(c workflow.RunData) error {
 
 	initCfg, client, ignorePreflightErrors := data.InitCfg(), data.Client(), data.IgnorePreflightErrors()
 
-	// First, check if we're root separately from the other preflight checks and fail fast
+	// First, check if we're root separately from the other preflight checks and fail fast.
 	if err := preflight.RunRootCheckOnly(ignorePreflightErrors); err != nil {
 		return err
 	}
 
-	// Run CoreDNS migration check
+	// Run CoreDNS migration check.
 	if err := upgrade.RunCoreDNSMigrationCheck(client, ignorePreflightErrors); err != nil {
 		return err
 	}
 
-	// Run healthchecks against the cluster
+	// Run healthchecks against the cluster.
 	klog.V(1).Infoln("[upgrade/preflight] Verifying the cluster health")
 	if err := upgrade.CheckClusterHealth(client, &initCfg.ClusterConfiguration, ignorePreflightErrors, printer); err != nil {
 		return err
 	}
 
-	// Check if feature gate flags used in the cluster are consistent with the set of features currently supported by kubeadm
+	// Check if feature gate flags used in the cluster are consistent with the set of features currently supported by kubeadm.
 	if msg := features.CheckDeprecatedFlags(&features.InitFeatureGates, initCfg.FeatureGates); len(msg) > 0 {
 		for _, m := range msg {
 			_, _ = printer.Printf("[upgrade/preflight] %s\n", m)
 		}
 	}
 
-	// Validate requested and validate actual version
+	// Validate requested and validate actual version.
 	klog.V(1).Infoln("[upgrade/preflight] Validating requested and actual version")
 	if err := configutil.NormalizeKubernetesVersion(&initCfg.ClusterConfiguration); err != nil {
 		return err
@@ -132,8 +132,8 @@ func runPreflight(c workflow.RunData) error {
 	return nil
 }
 
-// enforceVersionPolicies makes sure that the version the user specified is valid to upgrade to
-// There are both fatal and skippable (with --force) errors
+// enforceVersionPolicies makes sure that the version the user specified is valid to upgrade to.
+// It handles both fatal and skippable (with --force) errors.
 func enforceVersionPolicies(newK8sVersionStr string, newK8sVersion *version.Version, allowExperimentalUpgrades, allowRCUpgrades, force bool, versionGetter upgrade.VersionGetter) error {
 	fmt.Printf("[upgrade/preflight] You have chosen to upgrade the cluster version to %q\n", newK8sVersionStr)
 
@@ -146,12 +146,12 @@ func enforceVersionPolicies(newK8sVersionStr string, newK8sVersion *version.Vers
 		}
 
 		if len(versionSkewErrs.Skippable) > 0 {
-			// Return the error if the user hasn't specified the --force flag
+			// Return the error if the user hasn't specified the --force flag.
 			if !force {
 				return errors.Errorf("the version argument is invalid due to these errors:\n\n%v\nCan be bypassed if you pass the --force flag",
 					kubeadmutil.FormatErrMsg(versionSkewErrs.Skippable))
 			}
-			// Soft errors found, but --force was specified
+			// Soft errors found, but --force was specified.
 			fmt.Printf("[upgrade/preflight] Found %d potential version compatibility errors but skipping since the --force flag is set: \n\n%v", len(versionSkewErrs.Skippable), kubeadmutil.FormatErrMsg(versionSkewErrs.Skippable))
 		}
 	}
diff --git a/cmd/kubeadm/app/cmd/phases/upgrade/apply/uploadconfig.go b/cmd/kubeadm/app/cmd/phases/upgrade/apply/uploadconfig.go
index 16e6470ebc0..525113d3eb2 100644
--- a/cmd/kubeadm/app/cmd/phases/upgrade/apply/uploadconfig.go
+++ b/cmd/kubeadm/app/cmd/phases/upgrade/apply/uploadconfig.go
@@ -72,7 +72,7 @@ func getUploadConfigPhaseFlags() []string {
 	}
 }
 
-// runUploadKubeadmConfig uploads the kubeadm configuration to a ConfigMap
+// runUploadKubeadmConfig uploads the kubeadm configuration to a ConfigMap.
 func runUploadKubeadmConfig(c workflow.RunData) error {
 	cfg, client, dryRun, err := getUploadConfigData(c)
 	if err != nil {
@@ -91,7 +91,7 @@ func runUploadKubeadmConfig(c workflow.RunData) error {
 	return nil
 }
 
-// runUploadKubeletConfig uploads the kubelet configuration to a ConfigMap
+// runUploadKubeletConfig uploads the kubelet configuration to a ConfigMap.
 func runUploadKubeletConfig(c workflow.RunData) error {
 	cfg, client, dryRun, err := getUploadConfigData(c)
 	if err != nil {
@@ -109,7 +109,7 @@ func runUploadKubeletConfig(c workflow.RunData) error {
 		return errors.Wrap(err, "error creating kubelet configuration ConfigMap")
 	}
 
-	klog.V(1).Infoln("[upgrade/upload-config] Preserving the CRISocket information for the control-plane node")
+	klog.V(1).Infoln("[upgrade/upload-config] Preserving the CRISocket information for this control-plane node")
 	if err := patchnodephase.AnnotateCRISocket(client, cfg.NodeRegistration.Name, cfg.NodeRegistration.CRISocket); err != nil {
 		return errors.Wrap(err, "error writing Crisocket information for the control-plane node")
 	}
diff --git a/cmd/kubeadm/app/cmd/upgrade/apply.go b/cmd/kubeadm/app/cmd/upgrade/apply.go
index 41b81ec5eef..10b0d4113ff 100644
--- a/cmd/kubeadm/app/cmd/upgrade/apply.go
+++ b/cmd/kubeadm/app/cmd/upgrade/apply.go
@@ -139,8 +139,8 @@ func newCmdApply(apf *applyPlanFlags) *cobra.Command {
 	applyRunner.AppendPhase(phases.NewAddonPhase())
 	applyRunner.AppendPhase(phases.NewPostUpgradePhase())
 
-	// Sets the data builder function, that will be used by the runner
-	// both when running the entire workflow or single phases
+	// Sets the data builder function, that will be used by the runner,
+	// both when running the entire workflow or single phases.
 	applyRunner.SetDataInitializer(func(cmd *cobra.Command, args []string) (workflow.RunData, error) {
 		data, err := newApplyData(cmd, args, flags)
 		if err != nil {
@@ -154,7 +154,7 @@ func newCmdApply(apf *applyPlanFlags) *cobra.Command {
 	})
 
 	// Binds the Runner to kubeadm upgrade apply command by altering
-	// command help, adding --skip-phases flag and by adding phases subcommands
+	// command help, adding --skip-phases flag and by adding phases subcommands.
 	applyRunner.BindToCommand(cmd)
 
 	return cmd
@@ -170,7 +170,7 @@ func newApplyData(cmd *cobra.Command, args []string, applyFlags *applyFlags) (*a
 	}
 
 	upgradeVersion := upgradeCfg.Apply.KubernetesVersion
-	// The version arg is mandatory, unless it's specified in the config file
+	// The version arg is mandatory, unless it's specified in the config file.
 	if upgradeVersion == "" {
 		if err := cmdutil.ValidateExactArgNumber(args, []string{"version"}); err != nil {
 			return nil, err
@@ -229,7 +229,7 @@ func newApplyData(cmd *cobra.Command, args []string, applyFlags *applyFlags) (*a
 
 	printer := &output.TextPrinter{}
 
-	// Fetches the cluster configuration
+	// Fetches the cluster configuration.
 	klog.V(1).Infoln("[upgrade] retrieving configuration from cluster")
 	initCfg, err := configutil.FetchInitConfigurationFromCluster(client, nil, "upgrade", false, false)
 	if err != nil {
@@ -238,7 +238,7 @@ func newApplyData(cmd *cobra.Command, args []string, applyFlags *applyFlags) (*a
 			_, _ = printer.Printf("[upgrade] Use 'kubeadm init phase upload-config --config your-config.yaml' to re-upload it.\n")
 			err = errors.Errorf("the ConfigMap %q in the %q namespace was not found", constants.KubeadmConfigConfigMap, metav1.NamespaceSystem)
 		}
-		return nil, errors.Wrap(err, "[upgrade/init config] FATAL")
+		return nil, errors.Wrap(err, "[upgrade] FATAL")
 	}
 
 	// Also set the union of pre-flight errors to InitConfiguration, to provide a consistent view of the runtime configuration:
diff --git a/cmd/kubeadm/app/cmd/upgrade/apply_test.go b/cmd/kubeadm/app/cmd/upgrade/apply_test.go
index d5a80f23c08..460cc7cc38a 100644
--- a/cmd/kubeadm/app/cmd/upgrade/apply_test.go
+++ b/cmd/kubeadm/app/cmd/upgrade/apply_test.go
@@ -112,7 +112,7 @@ func TestNewApplyData(t *testing.T) {
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			// initialize an external apply flags and inject it to the apply cmd
+			// Initialize an external apply flags and inject it to the apply cmd.
 			apf := &applyPlanFlags{
 				kubeConfigPath:            kubeadmconstants.GetAdminKubeConfigPath(),
 				cfgPath:                   "",
@@ -125,7 +125,7 @@ func TestNewApplyData(t *testing.T) {
 
 			cmd := newCmdApply(apf)
 
-			// sets cmd flags (that will be reflected on the init options)
+			// Sets cmd flags (that will be reflected on the init options).
 			for f, v := range tc.flags {
 				_ = cmd.Flags().Set(f, v)
 			}
@@ -136,7 +136,7 @@ func TestNewApplyData(t *testing.T) {
 				renewCerts:     true,
 			}
 
-			// test newApplyData method
+			// Test newApplyData method.
 			data, err := newApplyData(cmd, tc.args, flags)
 			if err == nil && len(tc.expectedError) != 0 {
 				t.Error("Expected error, but got success")
@@ -145,7 +145,7 @@ func TestNewApplyData(t *testing.T) {
 				t.Fatalf("newApplyData returned unexpected error, expected: %s, got %v", tc.expectedError, err)
 			}
 
-			// exec additional validation on the returned value
+			// Exec additional validation on the returned value.
 			if tc.validate != nil {
 				tc.validate(t, data)
 			}
diff --git a/cmd/kubeadm/app/phases/bootstraptoken/node/tlsbootstrap.go b/cmd/kubeadm/app/phases/bootstraptoken/node/tlsbootstrap.go
index c3e9d4d4a3b..19a3eb63c94 100644
--- a/cmd/kubeadm/app/phases/bootstraptoken/node/tlsbootstrap.go
+++ b/cmd/kubeadm/app/phases/bootstraptoken/node/tlsbootstrap.go
@@ -49,7 +49,7 @@ func AllowBootstrapTokensToPostCSRs(client clientset.Interface) error {
 	})
 }
 
-// AllowBootstrapTokensToGetNodes creates RBAC rules to allow Node Bootstrap Tokens to list nodes
+// AllowBootstrapTokensToGetNodes creates RBAC rules to allow Node Bootstrap Tokens to list nodes.
 func AllowBootstrapTokensToGetNodes(client clientset.Interface) error {
 	fmt.Println("[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes")
 
diff --git a/cmd/kubeadm/app/phases/upgrade/postupgrade.go b/cmd/kubeadm/app/phases/upgrade/postupgrade.go
index 520335af886..cf5ad4c219b 100644
--- a/cmd/kubeadm/app/phases/upgrade/postupgrade.go
+++ b/cmd/kubeadm/app/phases/upgrade/postupgrade.go
@@ -109,7 +109,7 @@ func PerformAddonsUpgrade(client clientset.Interface, cfg *kubeadmapi.InitConfig
 	return errorsutil.NewAggregate(errs)
 }
 
-// UnupgradedControlPlaneInstances returns a list of control palne instances that have not yet been upgraded.
+// UnupgradedControlPlaneInstances returns a list of control plane instances that have not yet been upgraded.
 //
 // NB. This function can only be called after the current control plane instance has been upgraded already.
 // Because it determines whether the other control plane instances have been upgraded by checking whether