Linux 4.5 has been released. This release adds a new copy_file_range() system call that allows to make copies of files without transferring data through userspace; experimental Powerplay power management for modern Radeon GPUs; scalability improvements in the Btrfs free space handling; support GCC's Undefined Behavior Sanitizer (-fsanitize=undefined); Forwarded Error Correction support in the device-mapper's verity target; support for the MADV_FREE flag in madvise(); the new cgroup unified hierarchy is considered stable; scalability improvements for SO_REUSEPORT UDP sockets; scalability improvements for epoll, and better memory accounting of sockets in the memory controller. There are also new drivers and many other small improvements.
There are also new drivers and many other small improvements. Here is the full list of changes.