[GIT PULL membarrier/urgent] membarrier commits for 4.14

[Paul E. McKenney]

Hello, Ingo,

This urgent pull request contains three commits that fix a problem
that arose when designing requested extensions to sys_membarrier()
to allow JITs to efficiently flush old code from instruction caches.
Several potential algorithms are much less painful if the user register
intent to use this functionality early on, for example, before the process
spawns the second thread.  Registering at this time removes the need to
interrupt each and every thread in that process at the first expedited
sys_membarrier() system call.

However, if we let the current function out, then user programs might be
written without registration, which would make it more difficult to add
required registration after the fact.  Hence the late-in-merge-window
pull request.

These have been subject to 0day test robot and -next testing and
are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git urgent-for-mingo

for you to fetch changes up to 204a0fa1a3ecd9244869fa67608ad4fda232cba1:

  membarrier: Document scheduler barrier requirements (2017-10-04 11:02:18 -0700)

----------------------------------------------------------------
Mathieu Desnoyers (3):
      membarrier: Provide register expedited private command
      membarrier: selftest: Test private expedited cmd
      membarrier: Document scheduler barrier requirements

 MAINTAINERS                                        |   2 +
 arch/powerpc/Kconfig                               |   1 +
 arch/powerpc/include/asm/membarrier.h              |  43 ++++++++
 arch/powerpc/include/asm/thread_info.h             |   3 +
 arch/powerpc/kernel/Makefile                       |   2 +
 arch/powerpc/kernel/membarrier.c                   |  45 +++++++++
 arch/powerpc/mm/mmu_context.c                      |   7 ++
 arch/x86/mm/tlb.c                                  |   5 +
 fs/exec.c                                          |   1 +
 include/linux/mm_types.h                           |   3 +
 include/linux/sched/mm.h                           |  55 +++++++++++
 include/uapi/linux/membarrier.h                    |  23 +++--
 init/Kconfig                                       |   3 +
 kernel/fork.c                                      |   2 +
 kernel/sched/core.c                                |  47 +++++----
 kernel/sched/membarrier.c                          |  25 ++++-
 .../testing/selftests/membarrier/membarrier_test.c | 109 ++++++++++++++++++---
 17 files changed, 329 insertions(+), 47 deletions(-)
 create mode 100644 arch/powerpc/include/asm/membarrier.h
 create mode 100644 arch/powerpc/kernel/membarrier.c