The __munlock_pagevec function in mm/mlock.c in the Linux kernel before 4.11.4 allows local users to cause a denial of service (NR_MLOCK accounting corruption) via crafted use of mlockall and munlockall system calls.
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.11.4
https://usn.ubuntu.com/3655-2/
https://usn.ubuntu.com/3655-1/
https://github.com/torvalds/linux/commit/70feee0e1ef331b22cc51f383d532a0d043fbdcc