[PATCHv4 00/12] Do not lose dirty bit on THP pages

Kirill A. Shutemov
2017-12-13T10:57:44Z

Vlastimil noted that pmdp_invalidate() is not atomic and we can lose
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
mm/thp: Remove pmd_huge_split_prepare

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 lose 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.

Nitin Gupta (1):
sparc64: Update pmdp_invalidate() to return old pmd 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/hash-4k.h | 2 -
arch/powerpc/include/asm/book3s/64/hash-64k.h | 2 -
arch/powerpc/include/asm/book3s/64/pgtable.h | 13 +----
arch/powerpc/include/asm/book3s/64/radix.h | 6 --
arch/powerpc/mm/pgtable-book3s64.c | 7 ++-
arch/powerpc/mm/pgtable-hash64.c | 22 -------
arch/s390/include/asm/pgtable.h | 4 +-
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 | 25 +++++---
mm/huge_memory.c | 83 ++++++++++++---------------
mm/pgtable-generic.c | 6 +-
19 files changed, 156 insertions(+), 115 deletions(-)

--
2.15.0

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