Patching with Ronnie Sahlberg's f74bc7c[1] on top of the otherwise affected Debian linux-image-4.14.0-rc7-amd64 using the handbook test-patches instructions[2] fixes this bug for me. This was merged upstream in 89db69d yesterday, and should be included in the next -rc or 4.14.0 proper.
[1] https://github.com/torvalds/linux/commit/f74bc7c6679200a4a83156bb89cbf6c229fe8ec0.patch [2] https://kernel-handbook.alioth.debian.org/ch-common-tasks.html#s4.2.2 -- Andrew Chadwick
