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Groups > linux.kernel > #1208639

[PATCHv2 0/4] Fix compound_head() race

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Here's my attempt on fixing recently discovered race in compound_head().
It should make compound_head() reliable in all contexts.

The patchset is against Linus' tree. Let me know if it need to be rebased
onto different baseline.

It's expected to have conflicts with my page-flags patchset and probably
should be applied before it.

v2: Per Hugh's suggestion page->compound_head is moved into third double
    word. This way we can avoid memory overhead which v1 had in some
    cases.

    This place in struct page is rather overloaded. More testing is
    required to make sure we don't collide with anyone.

Kirill A. Shutemov (4):
  mm: drop page->slab_page
  zsmalloc: use page->private instead of page->first_page
  mm: pack compound_dtor and compound_order into one word in struct page
  mm: make compound_head() robust

 Documentation/vm/split_page_table_lock |  4 +-
 arch/xtensa/configs/iss_defconfig      |  1 -
 include/linux/mm.h                     | 75 +++++++++----------------------
 include/linux/mm_types.h               | 20 ++++++---
 include/linux/page-flags.h             | 80 ++++++++--------------------------
 mm/Kconfig                             | 12 -----
 mm/debug.c                             |  5 ---
 mm/huge_memory.c                       |  3 +-
 mm/hugetlb.c                           | 16 +++----
 mm/internal.h                          |  4 +-
 mm/memory-failure.c                    |  7 ---
 mm/page_alloc.c                        | 37 ++++++++++------
 mm/swap.c                              |  4 +-
 mm/zsmalloc.c                          | 11 +++--
 14 files changed, 94 insertions(+), 185 deletions(-)

-- 
2.5.0

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[PATCHv2 0/4] Fix compound_head() race "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-08-17 17:10 +0200
  [PATCHv2 3/4] mm: pack compound_dtor and compound_order into one word in struct page "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-08-17 17:10 +0200
    Re: [PATCHv2 3/4] mm: pack compound_dtor and compound_order into  one word in struct page Hugh Dickins <hughd@google.com> - 2015-08-18 01:10 +0200
    Re: [PATCHv2 3/4] mm: pack compound_dtor and compound_order into one  word in struct page Michal Hocko <mhocko@kernel.org> - 2015-08-18 17:50 +0200
      Re: [PATCHv2 3/4] mm: pack compound_dtor and compound_order into one  word in struct page "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-08-18 20:30 +0200
    Re: [PATCHv2 3/4] mm: pack compound_dtor and compound_order into one  word in struct page Michal Hocko <mhocko@kernel.org> - 2015-08-18 18:10 +0200
      Re: [PATCHv2 3/4] mm: pack compound_dtor and compound_order into one  word in struct page "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-08-18 20:30 +0200
  [PATCHv2 2/4] zsmalloc: use page->private instead of page->first_page "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-08-17 17:10 +0200
  [PATCHv2 4/4] mm: make compound_head() robust "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-08-17 17:20 +0200
    Re: [PATCHv2 4/4] mm: make compound_head() robust Michal Hocko <mhocko@kernel.org> - 2015-08-18 13:30 +0200
      Re: [PATCHv2 4/4] mm: make compound_head() robust Michal Hocko <mhocko@kernel.org> - 2015-08-18 18:50 +0200
        Re: [PATCHv2 4/4] mm: make compound_head() robust "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-08-18 20:30 +0200

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