According to Linus Torvalds Linux Kernel 4.2 may be the biggest release, as he stated on his Google Plus page.
Yesterday evening Linus Torvalds revealed interesting information about the next major version of the Linux kernel, which will be released within a few days as the first release candidate version.
On his Google Plus page Linux Torvalds states “4.0 was pretty small (by our modern standards, which is to say it was still a lot of changes), 4.1 was about average, and it looks like 4.2 may end up being the biggest release (in number of commits, at least) we’ve ever had.”