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* [PATCH v11 0/4] fix double page fault in cow_user_page for pfn mapping
@ 2019-10-09  8:42 Jia He
  2019-10-09  8:42 ` [PATCH v11 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
                   ` (3 more replies)
  0 siblings, 4 replies; 10+ messages in thread
From: Jia He @ 2019-10-09  8:42 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Mark Rutland, James Morse,
	Marc Zyngier, Matthew Wilcox, Kirill A. Shutemov,
	linux-arm-kernel, linux-kernel, linux-mm, Suzuki Poulose,
	Borislav Petkov, H. Peter Anvin, x86
  Cc: Thomas Gleixner, Andrew Morton, hejianet, Kaly Xin, nd, Jia He

When we tested pmdk unit test vmmalloc_fork TEST1 in arm64 guest, there
will be a double page fault in __copy_from_user_inatomic of cow_user_page.

As told by Catalin: "On arm64 without hardware Access Flag, copying from
user will fail because the pte is old and cannot be marked young. So we
always end up with zeroed page after fork() + CoW for pfn mappings. we
don't always have a hardware-managed access flag on arm64."

Changes
v11:
    refine cpu_has_hw_af in PATCH 01(Will Deacon, Suzuki)
    change the default return value to true in arch_faults_on_old_pte
    add PATCH 03 for overriding arch_faults_on_old_pte(false) on x86
v10:
    add r-b from Catalin and a-b from Kirill in PATCH 03
    remoe Reported-by in PATCH 01
v9: refactor cow_user_page for indention optimization (Catalin)
    hold the ptl longer (Catalin)
v8: change cow_user_page's return type (Matthew)
v7: s/pte_spinlock/pte_offset_map_lock (Kirill)
v6: fix error case of returning with spinlock taken (Catalin)
    move kmap_atomic to avoid handling kunmap_atomic
v5: handle the case correctly when !pte_same
    fix kbuild test failed
v4: introduce cpu_has_hw_af (Suzuki)
    bail out if !pte_same (Kirill)
v3: add vmf->ptl lock/unlock (Kirill A. Shutemov)
    add arch_faults_on_old_pte (Matthew, Catalin)
v2: remove FAULT_FLAG_WRITE when setting pte access flag (Catalin)

Jia He (4):
  arm64: cpufeature: introduce helper cpu_has_hw_af()
  arm64: mm: implement arch_faults_on_old_pte() on arm64
  x86/mm: implement arch_faults_on_old_pte() stub on x86
  mm: fix double page fault on arm64 if PTE_AF is cleared

 arch/arm64/include/asm/cpufeature.h |  14 ++++
 arch/arm64/include/asm/pgtable.h    |  14 ++++
 arch/x86/include/asm/pgtable.h      |   6 ++
 mm/memory.c                         | 104 ++++++++++++++++++++++++----
 4 files changed, 123 insertions(+), 15 deletions(-)

-- 
2.17.1



^ permalink raw reply	[flat|nested] 10+ messages in thread

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Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-09  8:42 [PATCH v11 0/4] fix double page fault in cow_user_page for pfn mapping Jia He
2019-10-09  8:42 ` [PATCH v11 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-10-10 16:43   ` Catalin Marinas
2019-10-11  1:16     ` Justin He (Arm Technology China)
2019-10-11 10:38       ` Catalin Marinas
2019-10-11 13:51         ` Justin He (Arm Technology China)
2019-10-09  8:42 ` [PATCH v11 2/4] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-10-09  8:42 ` [PATCH v11 3/4] x86/mm: implement arch_faults_on_old_pte() stub on x86 Jia He
2019-10-09  8:42 ` [PATCH v11 4/4] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-10-10 16:45   ` Catalin Marinas

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