[PATCH 0/4] thp: fix few MADV_DONTNEED races

[Kirill A. Shutemov]

For MADV_DONTNEED to work properly with huge pages, it's critical to not clear
pmd intermittently unless you hold down_write(mmap_sem). Otherwise
MADV_DONTNEED can miss the THP which can lead to userspace breakage.

See example of such race in commit message of patch 2/4.

All these races are found by code inspection. I haven't seen them triggered. 
I don't think it's worth to apply them to stable@.

Kirill A. Shutemov (4):
  thp: reduce indentation level in change_huge_pmd()
  thp: fix MADV_DONTNEED vs. numa balancing race
  thp: fix MADV_DONTNEED vs. MADV_FREE race
  thp: fix MADV_DONTNEED vs clear soft dirty race

 fs/proc/task_mmu.c |  9 +++++-
 mm/huge_memory.c   | 86 ++++++++++++++++++++++++++++++++++++------------------
 2 files changed, 66 insertions(+), 29 deletions(-)

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2.11.0