([#44744](https://github.com/kubernetes/kubernetes/pull/44744), [@yguo0905](https://github.com/yguo0905))

  * Kubernetes now shares a single PID namespace among all containers in a pod when running with docker >= 1.13.1. This means processes can now signal processes in other containers in a pod, but it also means that the `kubectl exec {pod} kill 1` pattern will cause the Pod to be restarted rather than a single container. ([#45236](https://github.com/kubernetes/kubernetes/pull/45236), [@verb](...

for COS images on GCE has changed to `/home/kubernetes/flexvolume`, rather than `/etc/srv/kubernetes/kubelet-plugins/volume/exec`. Existing Flexvolume installations in clusters using COS images must be moved to the new directory, and installation processes must be updated with the new path. ([#58171](https://github.com/kubernetes/kubernetes/pull/58171), [@verult](https://github.com/verult))

* Default values differ between the Kubelet's componentconfig (config file) API and the Kubelet's...

- Added `singleProcessOOMKill` flag to the kubelet configuration. Setting that to true enable single process OOM killing in cgroups v2. In this mode, if a single process is OOM killed within a container, the remaining processes will not be OOM killed. ([#126096](https://github.com/kubernetes/kubernetes/pull/126096), [@utam0k](https://github.com/utam0k)) [SIG API Machinery, Node, Testing and Windows]

- Updating kubelet permissions check for Windows nodes to see if process is elevated instead of checking if process owner is in Administrators group ([#111078](https://github.com/kubernetes/kubernetes/pull/111078), [@marosset](https://github.com/marosset)) [SIG Node and Windows]

## Dependencies

### Added

- GCE/Windows: When the service cannot be stopped Stackdriver logging processes are now force killed ([#77378](https://github.com/kubernetes/kubernetes/pull/77378), [@yujuhong](https://github.com/yujuhong))

    * Each deployment method should bind users/groups to the ClusterRoles if they are using this feature.
* Adds AllowPrivilegeEscalation to control whether a process can gain more privileges than its parent process ([#47019](https://github.com/kubernetes/kubernetes/pull/47019), [@jessfraz](https://github.com/jessfraz))

### SIG-cloud-provider

This is the first Kubernetes release for this SIG! In v1.12, SIG Cloud Provider focused on building the processes and infrastructure to better support existing and new cloud providers. Some of these initiatives (many of which are still in progress) are:

- If using cgroups v2, then the cgroup aware OOM killer will be enabled for container cgroups via  `memory.oom.group` .  This causes processes within the cgroup to be treated as a unit and killed simultaneously in the event of an OOM kill on any process in the cgroup. ([#117793](https://github.com/kubernetes/kubernetes/pull/117793), [@tzneal](https://github.com/tzneal)) [SIG Apps, Node and Testing]

- Supported fine-grained supplemental groups policy (KEP-3619), which enabled
  fine-grained control for supplementary groups in the first container processes.
  This allows you to choose whether to include groups defined in the container image (/etc/groups)

    * controller REST client now uses that version.  For v1beta1, the API is now known as
    * resource-metrics.metrics.k8s.io.
* In GCE with COS, increase TasksMax for Docker service to raise cap on number of threads/processes used by containers. ([#51986](https://github.com/kubernetes/kubernetes/pull/51986), [@yujuhong](https://github.com/yujuhong))