linux-kernel - [PATCHv3 00/11] Do not loose dirty bit on THP pages

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Message-Id: <20170912153941.47012-1-kirill.shutemov@linux.intel.com>
Date:   Tue, 12 Sep 2017 18:39:30 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vineet Gupta <vgupta@...opsys.com>,
        Russell King <linux@...linux.org.uk>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>
Cc:     linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv3 00/11] Do not loose dirty bit on THP pages

Vlastimil noted that pmdp_invalidate() is not atomic and we can loose
dirty and access bits if CPU sets them after pmdp dereference, but
before set_pmd_at().

The bug can lead to data loss, but the race window is tiny and I haven't
seen any reports that suggested that it happens in reality. So I don't
think it worth sending it to stable.

Unfortunately, there's no way to address the issue in a generic way. We need to
fix all architectures that support THP one-by-one.

All architectures that have THP supported have to provide atomic
pmdp_invalidate() that returns previous value.

If generic implementation of pmdp_invalidate() is used, architecture needs to
provide atomic pmdp_estabish().

pmdp_estabish() is not used out-side generic implementation of
pmdp_invalidate() so far, but I think this can change in the future.

Aneesh Kumar K.V (2):
  powerpc/mm: update pmdp_invalidate to return old pmd value
  sparc64: update pmdp_invalidate to return old pmd value

Catalin Marinas (1):
  arm64: Provide pmdp_establish() helper

Kirill A. Shutemov (7):
  asm-generic: Provide generic_pmdp_establish()
  arc: Use generic_pmdp_establish as pmdp_establish
  arm/mm: Provide pmdp_establish() helper
  mips: Use generic_pmdp_establish as pmdp_establish
  x86/mm: Provide pmdp_establish() helper
  mm: Do not loose dirty and access bits in pmdp_invalidate()
  mm: Use updated pmdp_invalidate() interface to track dirty/accessed
    bits

Martin Schwidefsky (1):
  s390/mm: Modify pmdp_invalidate to return old value.

 arch/arc/include/asm/hugepage.h              |  3 +++
 arch/arm/include/asm/pgtable-3level.h        |  3 +++
 arch/arm64/include/asm/pgtable.h             |  7 ++++++
 arch/mips/include/asm/pgtable.h              |  3 +++
 arch/powerpc/include/asm/book3s/64/pgtable.h |  4 +--
 arch/powerpc/mm/pgtable-book3s64.c           |  7 ++++--
 arch/s390/include/asm/pgtable.h              |  5 ++--
 arch/sparc/include/asm/pgtable_64.h          |  2 +-
 arch/sparc/mm/tlb.c                          | 23 +++++++++++++----
 arch/x86/include/asm/pgtable-3level.h        | 37 +++++++++++++++++++++++++++-
 arch/x86/include/asm/pgtable.h               | 15 +++++++++++
 fs/proc/task_mmu.c                           |  8 +++---
 include/asm-generic/pgtable.h                | 17 ++++++++++++-
 mm/huge_memory.c                             | 29 +++++++++-------------
 mm/pgtable-generic.c                         |  6 ++---
 15 files changed, 131 insertions(+), 38 deletions(-)

-- 
2.14.1