From: Jia He <justin.he@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: "Ralph Campbell" <rcampbell@nvidia.com>,
"Jia He" <justin.he@arm.com>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
"Alex Van Brunt" <avanbrunt@nvidia.com>,
"Kaly Xin" <Kaly.Xin@arm.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Punit Agrawal" <punitagrawal@gmail.com>,
hejianet@gmail.com, "Andrew Morton" <akpm@linux-foundation.org>,
"Robin Murphy" <robin.murphy@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>
Subject: [PATCH v5 0/3] fix double page fault on arm64
Date: Fri, 20 Sep 2019 00:12:01 +0800 [thread overview]
Message-ID: <20190919161204.142796-1-justin.he@arm.com> (raw)
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
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 (by Kirill A. Shutemov)
add arch_faults_on_old_pte (Matthew, Catalin)
v2: remove FAULT_FLAG_WRITE when setting pte access flag (by Catalin)
Jia He (3):
arm64: cpufeature: introduce helper cpu_has_hw_af()
arm64: mm: implement arch_faults_on_old_pte() on arm64
mm: fix double page fault on arm64 if PTE_AF is cleared
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/pgtable.h | 12 ++++++
arch/arm64/kernel/cpufeature.c | 10 +++++
mm/memory.c | 59 ++++++++++++++++++++++++++---
4 files changed, 77 insertions(+), 5 deletions(-)
--
2.17.1
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next reply other threads:[~2019-09-19 16:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 16:12 Jia He [this message]
2019-09-19 16:12 ` [PATCH v5 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-09-19 16:36 ` Catalin Marinas
2019-09-20 1:14 ` Justin He (Arm Technology China)
2019-09-19 16:12 ` [PATCH v5 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-09-19 16:12 ` [PATCH v5 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-09-19 16:42 ` Catalin Marinas
2019-09-20 1:13 ` Justin He (Arm Technology China)
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