[RFC PATCH for 4.16 00/11] membarrier updates for 4.16

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

Hi,

I decided to split the membarrier updates from the rseq patchset, and
send it separately so each discussion can happen in different threads.

This series includes a fix for membarrier private expedited, which
should be merged into 4.15-rc and backported to 4.14. The fix has
also been sent separately.

Testing and documentation of membarrier is improved. A new shared
expedited membarrier command is added, allowing use of membarrier
expedited over shared memory mappings.

The series also introduces a "core serializing" private expedited
membarrier for JIT memory reclaim (currently on x86 and arm64).

Feedback is welcome!

Thanks,

Mathieu

Mathieu Desnoyers (11):
  Fix: membarrier: add missing preempt off around smp_call_function_many
  membarrier: selftest: Test private expedited cmd (v2)
  powerpc: membarrier: Skip memory barrier in switch_mm() (v7)
  membarrier: Document scheduler barrier requirements (v5)
  membarrier: provide SHARED_EXPEDITED command (v2)
  membarrier: selftest: Test shared expedited cmd
  membarrier: Provide core serializing command
  x86: Introduce sync_core_before_usermode (v2)
  membarrier: x86: Provide core serializing command (v3)
  membarrier: arm64: Provide core serializing command
  membarrier: selftest: Test private expedited sync core cmd

 MAINTAINERS                                        |   1 +
 arch/arm64/Kconfig                                 |   1 +
 arch/arm64/kernel/entry.S                          |   4 +
 arch/powerpc/Kconfig                               |   1 +
 arch/powerpc/include/asm/membarrier.h              |  27 +++
 arch/powerpc/mm/mmu_context.c                      |   7 +
 arch/x86/Kconfig                                   |   2 +
 arch/x86/entry/entry_32.S                          |   5 +
 arch/x86/entry/entry_64.S                          |   4 +
 arch/x86/include/asm/processor.h                   |  10 +
 arch/x86/mm/tlb.c                                  |   6 +
 include/linux/processor.h                          |   6 +
 include/linux/sched/mm.h                           |  40 +++-
 include/uapi/linux/membarrier.h                    |  66 +++++-
 init/Kconfig                                       |   9 +
 kernel/sched/core.c                                |  53 +++--
 kernel/sched/membarrier.c                          | 173 +++++++++++++--
 .../testing/selftests/membarrier/membarrier_test.c | 235 +++++++++++++++++++--
 18 files changed, 587 insertions(+), 63 deletions(-)
 create mode 100644 arch/powerpc/include/asm/membarrier.h

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2.11.0