Early this week, Linus released version 4.0 of the Linux Kernel. Now, this updated version of the Linux Kernel is available in the official Fedora repositories for users running the alpha release of Fedora 22.
To get the updated version of the kernel on your Fedora 22 machine, either update the system via the Software application (in Fedora Workstation), or using
dnf update on the command line.
UPDATE: Fedora Kernel Developer Josh Boyer recently posted about the 4.0 Kernel and Fedora. Check it out for further details about the 4.0 Kernel in Fedora.