* Add a feature to the scheduler to score fewer than all nodes in every scheduling cycle. This can improve performance of the scheduler in large clusters. ([#66733](https://github.com/kubernetes/kubernetes/pull/66733), [@bsalamat](https://github.com/bsalamat))

-->
```release-note

```

#### Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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- consumers of the 'certificatesigningrequests/approval' API must now have permission to 'approve' CSRs for the specific signer requested by the CSR. More information on the new signerName field and the required authorization can be found at https://kubernetes.io/docs/reference/access-authn-authz/certificate-signing-requests#authorization...

- the IP allocator in v1.17.0 can return errors such as `the cluster IP <ip> for service <service-name> is not within the service CIDR <cidr>; please recreate` in the logs of the kube-apiserver. The cause...

  
  **How can I migrate?**
  
  For backward compatibility, nil `QueueingHintFn` is treated as always returning QueueAfterBackoff. 
  So, if you want to just keep the existing behavior, you can register `ClusterEventWithHint` with no `QueueingHintFn` in it. 

### IPv4/IPv6 run

IPv4/IPv6 dual-stack has been reimplemented for 1.20 to support dual-stack Services, based on user and community feedback. If your cluster has dual-stack enabled, you can create Services which can use IPv4, IPv6, or both, and you can change this setting for existing Services. Details are available in updated [IPv4/IPv6 dual-stack docs](https://docs.k8s.io/concepts/services-networking/dual-stack/), which cover the nuanced array of options.

ference/scheduling/config) feature allows you to tune the algorithms and other settings of the kube-scheduler. You can easily enable or disable specific functionality (contained in plugins) in selected scheduling phases without having to rewrite the rest of the configuration. Furthermore, a single kube-scheduler instance can serve different configurations, called profiles. Pods can select the profile they want to be scheduled under via the `.spec.schedulerName` field.

### CSI Migration...

flag `--experimental-patches` is now deprecated and will be removed in a future release. You can migrate to using the new flag `--patches`. Add a new field `{Init|Join}Configuration.patches.directory` that can be used for the same purpose. For `init` and `join` it is now recommended that you migrate to configure patches via `{Init|Join}Configuration.patches.directory`. For the time being, these flags can be mixed with `--config`, but that might change in the future. On a command line, the last *patches...

* Use authorization to limit users' ability to use specific PodSecurityPolicy objects

**What is the impact?**

A user that is authorized to create pods can make use of any existing PodSecurityPolicy, even ones they are not authorized to use.

**How can I mitigate this prior to installing 1.5.5?**

1. Export existing PodSecurityPolicy objects:
  * `kubectl get podsecuritypolicies -o yaml > psp.yaml`

For example, a plugin that implements Score and Filter extensions can be simultaneously enabled for both.
This means entire plugins can be enabled and disabled without having to manually edit individual extension point settings.
These extension points can now be abstracted away due to their irrelevance for most users.

### CSI Migration updates