- Allow pods to use the `net.ipv4.tcp_rmem` and `net.ipv4.tcp_wmem` sysctl by default
  when the kernel version is 4.15 or higher. With the kernel 4.15 the sysctl became namespaced.

* The pod annotation `security.alpha.kubernetes.io/sysctls` now allows customization of namespaced and well isolated kernel parameters (sysctls), starting with `kernel.shm_rmid_forced`, `net.ipv4.ip_local_port_range` and `net.ipv4.tcp_syncookies` for Kubernetes 1.4. ([#27180](https://github.com/kubernetes/kubernetes/pull/27180), [@sttts](https://github.com/sttts))