Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH v3 0/2] fix double page fault on arm64
@ 2019-09-13 16:32 Jia He
  2019-09-13 16:32 ` [PATCH v3 1/2] arm64: mm: implement arch_faults_on_old_pte() " Jia He
  2019-09-13 16:32 ` [PATCH v3 2/2] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
  0 siblings, 2 replies; 7+ messages in thread
From: Jia He @ 2019-09-13 16:32 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
  Cc: Punit Agrawal, Anshuman Khandual, Jun Yao, Alex Van Brunt,
	Robin Murphy, Thomas Gleixner, Andrew Morton,
	Jérôme Glisse, Ralph Campbell, hejianet, 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
v3: add vmf->ptl lock/unlock (by Kirill A. Shutemov)
    add arch_faults_on_old_pte (Matthew, Catalins)
v2: remove FAULT_FLAG_WRITE when setting pte access flag (by Catalin)
Jia He (2):
  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/pgtable.h | 11 +++++++++++
 mm/memory.c                      | 29 ++++++++++++++++++++++++-----
 2 files changed, 35 insertions(+), 5 deletions(-)

-- 
2.17.1



^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, back to index

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-13 16:32 [PATCH v3 0/2] fix double page fault on arm64 Jia He
2019-09-13 16:32 ` [PATCH v3 1/2] arm64: mm: implement arch_faults_on_old_pte() " Jia He
2019-09-16  9:20   ` Kirill A. Shutemov
2019-09-13 16:32 ` [PATCH v3 2/2] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-09-16  9:16   ` Kirill A. Shutemov
2019-09-16  9:35     ` Justin He (Arm Technology China)
2019-09-16 14:16       ` Kirill A. Shutemov

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git