* Reimplement 'pause' in C - smaller footprint all around ([#23009](https://github.com/kubernetes/kubernetes/pull/23009), [@uluyol](https://github.com/uluyol))
* Add subPath to mount a child dir or file of a volumeMount ([#22575](https://github.com/kubernetes/kubernetes/pull/22575), [@MikaelCluseau](https://github.com/MikaelCluseau))

### Other notable changes

* Update the GCI image to gci-dev-55-8872-18-0 ([#35243](https://github.com/kubernetes/kubernetes/pull/35243), [@maisem](https://github.com/maisem))
* Change merge key for VolumeMount to mountPath ([#35071](https://github.com/kubernetes/kubernetes/pull/35071), [@thockin](https://github.com/thockin))

* PodSpecs containing parent directory references such as `..` (for example, `../bar`) in hostPath volume path or in volumeMount subpaths must be changed to the simple absolute path. Backsteps `..` are no longer allowed.([#47290](https://github.com/kubernetes/kubernetes/pull/47290), [@jhorwit2](https://github.com/jhorwit2)).


### API Machinery