[PATCH v3 0/2] mm: fixes of tlb_flush_pending races

[Nadav Amit <namit@vmware.com>]

These two patches address tlb_flush_pending issues. The first one address a
race when accessing tlb_flush_pending and is the important one.

The second patch addresses Andrew Morton question regarding the barriers. This
patch is not really related to the first one: the atomic operations
atomic_read() and atomic_inc() do not act as a memory barrier, and replacing
existing barriers with smp_mb__after_atomic() did not seem beneficial. Yet,
while reviewing the memory barriers around the use of tlb_flush_pending, few
issues were identified.


v2 -> v3:
 - Do not init tlb_flush_pending if it is not defined without (Sergey)
 - Internalize memory barriers to mm_tlb_flush_pending (Minchan) 

v1 -> v2:
 - Explain the implications of the implications of the race (Andrew)
 - Mark the patch that address the race as stable (Andrew)
 - Add another patch to clean the use of barriers (Andrew)


Nadav Amit (2):
  mm: migrate: prevent racy access to tlb_flush_pending
  mm: migrate: fix barriers around tlb_flush_pending

 arch/arm/include/asm/pgtable.h   |  3 ++-
 arch/arm64/include/asm/pgtable.h |  3 ++-
 arch/x86/include/asm/pgtable.h   |  2 +-
 include/linux/mm_types.h         | 39 +++++++++++++++++++++++++++------------
 kernel/fork.c                    |  4 +++-
 mm/debug.c                       |  2 +-
 mm/migrate.c                     |  2 +-
 7 files changed, 37 insertions(+), 18 deletions(-)

-- 
2.11.0

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