https://www.theregister.co.uk/2018/06/04/linux_4_17_released/

Linus Torvalds has decided the world’s not ready for version 5.0 of the Linux Kernel, so he’s given us version 4.17 instead.

Torvalds toyed with the idea of calling this release 5.0, because it passed the six million git objects mark. But he also said version numbers are meaningless and he might not call it 5.0.