[PATCH V3 0/4] arm64/mm: Convert pgtable READ_ONCE() as pxdp_get()

[PATCH V3 0/4] arm64/mm: Convert pgtable READ_ONCE() as pxdp_get()

[Anshuman Khandual]

Route READ_ONCE() accesses on pgtable entries via level specific generic MM
pxdp_get() helpers which platforms could then override when required. These
accessors on arm64, will help in ensuring page table accesses are performed
in an atomic manner while reading 128 bit page table entries later. But for
now they just default to READ_ONCE(), thus preserving existing behaviour on
current D64 translation a well.

This is similar to generic MM where all atomic accesses have already been
converted from READ_ONCE() into pgtable level specific accessors.

These are preparatory patches for D128 enablement, although standing their
own for D64 translation as well. These patches are split from earlier D128
V1 series. There are no functional changes here and besides mm kselftests
do not show any regression.

https://lore.kernel.org/linux-mm/20260729122452.3797443-1-anshuman.khandual@arm.com/

This series applies on v7.3-rc4 but after applying the following patches on
pgtable entry print standardization posted earlier.

https://lore.kernel.org/linux-mm/20260831054331.625505-1-anshuman.khandual@arm.com/

https://lore.kernel.org/linux-mm/20260916044933.2689426-1-anshuman.khandual@arm.com/

These patches have been hosted here as well.

git@git.gitlab.arm.com:linux-arm/linux-anshuman.git (arm64_pxdp_get_v3)

Changes in V3:

- Added overrides for pxdp_get() and replaced remaining READ_ONCE()
- Updated all commit messages as required
- Dropped previous tags

Changes in V2:

https://lore.kernel.org/all/20260922061638.3967467-1-anshuman.khandual@arm.com/

- Rebased on v7.3-rc4 along with all latest dependencies
- Updated commit messages per Ryan
- Added tags from Ryan

Changes in V1:

https://lore.kernel.org/all/20260903060657.2717457-1-anshuman.khandual@arm.com/

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Linu Cherian <linu.cherian@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org

Anshuman Khandual (4):
  arm64/mm: Use pmdp_get() for PMD accesses
  arm64/mm: Use pudp_get() for PUD accesses
  arm64/mm: Use p4dp_get() for P4D accesses
  arm64/mm: Use pgdp_get() for PGD accesses

 arch/arm64/include/asm/pgtable.h | 40 +++++++++++++++++----
 arch/arm64/mm/fault.c            |  8 ++---
 arch/arm64/mm/fixmap.c           |  6 ++--
 arch/arm64/mm/hugetlbpage.c      | 10 +++---
 arch/arm64/mm/kasan_init.c       | 18 +++++-----
 arch/arm64/mm/mmu.c              | 60 ++++++++++++++++----------------
 arch/arm64/mm/pageattr.c         |  8 ++---
 arch/arm64/mm/trans_pgd.c        | 14 ++++----
 8 files changed, 95 insertions(+), 69 deletions(-)

-- 
2.43.0

[PATCH V3 0/4] arm64/mm: Convert pgtable READ_ONCE() as pxdp_get()

[Anshuman Khandual]

Route READ_ONCE() accesses on pgtable entries via level specific generic MM
pxdp_get() helpers which platforms could then override when required. These
accessors on arm64, will help in ensuring page table accesses are performed
in an atomic manner while reading 128 bit page table entries later. But for
now they just default to READ_ONCE(), thus preserving existing behaviour on
current D64 translation a well.

This is similar to generic MM where all atomic accesses have already been
converted from READ_ONCE() into pgtable level specific accessors.

These are preparatory patches for D128 enablement, although standing their
own for D64 translation as well. These patches are split from earlier D128
V1 series. There are no functional changes here and besides mm kselftests
do not show any regression.

https://lore.kernel.org/linux-mm/20260729122452.3797443-1-anshuman.khandual@arm.com/

This series applies on v7.3-rc4 but after applying the following patches on
pgtable entry print standardization posted earlier.

https://lore.kernel.org/linux-mm/20260831054331.625505-1-anshuman.khandual@arm.com/

https://lore.kernel.org/linux-mm/20260916044933.2689426-1-anshuman.khandual@arm.com/

These patches have been hosted here as well.

git@git.gitlab.arm.com:linux-arm/linux-anshuman.git (arm64_pxdp_get_v3)

Changes in V3:

- Added overrides for pxdp_get() and replaced remaining READ_ONCE()
- Updated all commit messages as required
- Dropped previous tags

Changes in V2:

https://lore.kernel.org/all/20260922061638.3967467-1-anshuman.khandual@arm.com/

- Rebased on v7.3-rc4 along with all latest dependencies
- Updated commit messages per Ryan
- Added tags from Ryan

Changes in V1:

https://lore.kernel.org/all/20260903060657.2717457-1-anshuman.khandual@arm.com/

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Linu Cherian <linu.cherian@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org

Anshuman Khandual (4):
  arm64/mm: Use pmdp_get() for PMD accesses
  arm64/mm: Use pudp_get() for PUD accesses
  arm64/mm: Use p4dp_get() for P4D accesses
  arm64/mm: Use pgdp_get() for PGD accesses

 arch/arm64/include/asm/pgtable.h | 40 +++++++++++++++++----
 arch/arm64/mm/fault.c            |  8 ++---
 arch/arm64/mm/fixmap.c           |  6 ++--
 arch/arm64/mm/hugetlbpage.c      | 10 +++---
 arch/arm64/mm/kasan_init.c       | 18 +++++-----
 arch/arm64/mm/mmu.c              | 60 ++++++++++++++++----------------
 arch/arm64/mm/pageattr.c         |  8 ++---
 arch/arm64/mm/trans_pgd.c        | 14 ++++----
 8 files changed, 95 insertions(+), 69 deletions(-)

-- 
2.43.0

Re: [PATCH V3 0/4] arm64/mm: Convert pgtable READ_ONCE() as pxdp_get()

[Anshuman Khandual]

On Thu, Sep 24, 2026 at 11:52:10AM +0530, Anshuman Khandual wrote:
> Route READ_ONCE() accesses on pgtable entries via level specific generic MM
> pxdp_get() helpers which platforms could then override when required. These
> accessors on arm64, will help in ensuring page table accesses are performed
> in an atomic manner while reading 128 bit page table entries later. But for
> now they just default to READ_ONCE(), thus preserving existing behaviour on
> current D64 translation a well.
> 
> This is similar to generic MM where all atomic accesses have already been
> converted from READ_ONCE() into pgtable level specific accessors.
> 
> These are preparatory patches for D128 enablement, although standing their
> own for D64 translation as well. These patches are split from earlier D128
> V1 series. There are no functional changes here and besides mm kselftests
> do not show any regression.
> 
> https://lore.kernel.org/linux-mm/20260729122452.3797443-1-anshuman.khandual@arm.com/
> 
> This series applies on v7.3-rc4 but after applying the following patches on
> pgtable entry print standardization posted earlier.
> 
> https://lore.kernel.org/linux-mm/20260831054331.625505-1-anshuman.khandual@arm.com/
> 
> https://lore.kernel.org/linux-mm/20260916044933.2689426-1-anshuman.khandual@arm.com/

Hello Catalin/Andrew,

The above mentioned dependencies are already in mm-unstable, thus reflecting
in linux-next as well. Just to rule out merge conflict - this series applies
cleanly, builds and boots on latest tag next-20261002, which contains above
dependencies. But please do let me know if there are still some issues in
resolving this situation - will be happy to help. Thank you.

- Anshuman

> 
> These patches have been hosted here as well.
> 
> git@git.gitlab.arm.com:linux-arm/linux-anshuman.git (arm64_pxdp_get_v3)
> 
> Changes in V3:
> 
> - Added overrides for pxdp_get() and replaced remaining READ_ONCE()
> - Updated all commit messages as required
> - Dropped previous tags
> 
> Changes in V2:
> 
> https://lore.kernel.org/all/20260922061638.3967467-1-anshuman.khandual@arm.com/
> 
> - Rebased on v7.3-rc4 along with all latest dependencies
> - Updated commit messages per Ryan
> - Added tags from Ryan
> 
> Changes in V1:
> 
> https://lore.kernel.org/all/20260903060657.2717457-1-anshuman.khandual@arm.com/
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Ryan Roberts <ryan.roberts@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Lorenzo Stoakes <ljs@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@kernel.org>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Linu Cherian <linu.cherian@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> 
> Anshuman Khandual (4):
>   arm64/mm: Use pmdp_get() for PMD accesses
>   arm64/mm: Use pudp_get() for PUD accesses
>   arm64/mm: Use p4dp_get() for P4D accesses
>   arm64/mm: Use pgdp_get() for PGD accesses
> 
>  arch/arm64/include/asm/pgtable.h | 40 +++++++++++++++++----
>  arch/arm64/mm/fault.c            |  8 ++---
>  arch/arm64/mm/fixmap.c           |  6 ++--
>  arch/arm64/mm/hugetlbpage.c      | 10 +++---
>  arch/arm64/mm/kasan_init.c       | 18 +++++-----
>  arch/arm64/mm/mmu.c              | 60 ++++++++++++++++----------------
>  arch/arm64/mm/pageattr.c         |  8 ++---
>  arch/arm64/mm/trans_pgd.c        | 14 ++++----
>  8 files changed, 95 insertions(+), 69 deletions(-)
> 
> -- 
> 2.43.0
>