Merge pull request #42820 from pacoxu/patch-2

update swap related description before installation

Author: k8s-ci-robot

content/en/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md

@@ -26,8 +26,12 @@ see the [Creating a cluster with kubeadm](/docs/setup/production-environment/too
 * Full network connectivity between all machines in the cluster (public or private network is fine).
 * Unique hostname, MAC address, and product_uuid for every node. See [here](#verify-mac-address) for more details.
 * Certain ports are open on your machines. See [here](#check-required-ports) for more details.
-* Swap disabled. You **MUST** disable swap in order for the kubelet to work properly.
-    * For example, `sudo swapoff -a` will disable swapping temporarily. To make this change persistent across reboots, make sure swap is disabled in config files like `/etc/fstab`, `systemd.swap`, depending how it was configured on your system.
+* Swap configuration. The default behavior of a kubelet was to fail to start if swap memory was detected on a node.
+  Swap has been supported since v1.22. And since v1.28, Swap is supported for cgroup v2 only; the NodeSwap feature
+  gate of the kubelet is beta but disabled by default.
+  * You **MUST** disable swap if the kubelet is not properly configured to use swap. For example, `sudo swapoff -a`
+    will disable swapping temporarily. To make this change persistent across reboots, make sure swap is disabled in
+    config files like `/etc/fstab`, `systemd.swap`, depending how it was configured on your system.
 
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