I received this bug report today: https://bugs.archlinux.org/task/22351

"Opening or creating a luks encrypted partition fails with:

semid 1048580: semop failed for cookie 0xd4d3177: incorrect semaphore state
Failed to set a proper state for notification semaphore identified by
cookie value 223162743 (0xd4d3177) to initialize waiting for incoming
notifications."

I have no idea where to start (more details inside). Any ideas?