Because it’s almost Christmas, and the end of the year holidays are here, most Linux kernel developers took a short vacation to be with their family and friends, so Linux kernel 4.15 RC5 ended up being fairly normal, according to Linus Torvalds, except for an ongoing and noticeable merging of the x86 low-level preparation for kernel page table isolation. So a third of the RC5 patch is x86 updates. Besides the x86 updates, the fifth Release Candidate of Linux kernel 4.15 contains mostly updated drivers, various networking improvements for Berkeley Packet Filter (BPF) and selftests, as well some fixes for the XFS file system. You should study the appended shortlog to Linus Torvalds’ mailing list announcement if you’re curious to know what exactly was changed in this release.