Comment 5 for bug 1591804

The new interface is in v4.9:
5f23f6d x86/pkeys: Add self-tests
76de993 x86/pkeys: Allow configuration of init_pkru
acd547b x86/pkeys: Default to a restrictive init PKRU
c74fe39 pkeys: Add details of system call use to Documentation/
a60f7b6 generic syscalls: Wire up memory protection keys syscalls
f9afc61 x86: Wire up protection keys system calls
e8c24d3 x86/pkeys: Allocation/free syscalls
a8502b6 x86/pkeys: Make mprotect_key() mask off additional vm_flags
7d06d9c mm: Implement new pkey_mprotect() system call
e8c6226 x86/pkeys: Add fault handling for PF_PK page fault bit