* Fix bug that caused `kubectl` commands to sometimes fail to refresh access token when running against GKE clusters. ([#66314](https://github.com/kubernetes/kubernetes/pull/66314), [@jlowdermilk](https://github.com/jlowdermilk))

* Fix setup of configmap/secret/projected/downwardapi volumes ([#64855](https://github.com/kubernetes/kubernetes/pull/64855), [@gnufied](https://github.com/gnufied))

Kubeadm: during "init" an empty cgroupDriver value in the KubeletConfiguration is now always set to "systemd" unless the user is explicit about it. This requires existing machine setups to configure the container runtime to use the "systemd" driver. Documentation on this topic can be found here: https://kubernetes.io/docs/setup/production-environment/container-runtimes/. When upgrading existing clusters / nodes using "kubeadm upgrade" the old cgroupDriver value is preserved, but in 1.22 this change will...

    * kubeadm upgrade now successfully upgrades etcd and the controlplane to use TLS
    * kubeadm upgrade now supports external etcd setups
    * kubeadm upgrade can now rollback and restore etcd after an upgrade failure

For initial installations, see the [Setup topics](https://kubernetes.io/docs/setup/pick-right-solution/) in the Kubernetes documentation.

The `wait.NewExponentialBackoffManager` and `wait.NewJitteringBackoffManager` functions have been marked as deprecated.  Callers should switch to using the `Backoff{...}.DelayWithReset(clock, resetInterval)` method and must set the `Steps` field when using `Factor`. As a short term change, callers may use the `Timer()` method on the `BackoffManager` until the backoff managers are deprecated and removed. Please see the godoc of the deprecated functions for examples of how to replace...

- Kubeadm: increase robustness for "kubeadm join" when adding etcd members on slower setups ([#90645](https://github.com/kubernetes/kubernetes/pull/90645), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

 - Kubeadm: increase robustness for "kubeadm join" when adding etcd members on slower setups ([#90645](https://github.com/kubernetes/kubernetes/pull/90645), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

## Reporting a Vulnerability

Instructions for reporting a vulnerability can be found on the
[Kubernetes Security and Disclosure Information] page.

[Kubernetes version and version skew support policy]: https://kubernetes.io/docs/setup/release/version-skew-policy/#supported-versions

For initial installations, see the [Setup topics][] in the Kubernetes
documentation.

To upgrade to this release from a previous version, take any actions required
[Before Upgrading](#before-upgrading).

For more information about the release and for the latest documentation,
see the [Kubernetes documentation](https://kubernetes.io/docs/home/).

[Setup topics]: https://kubernetes.io/docs/setup/pick-right-solution/