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

[Ryan Roberts <ryan.roberts@arm.com>]

On 03/09/2026 07:06, 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.
> 
> 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 v3.7-rc1 but after applying the following patches

I assume you meant v7.3-rc1 here?

> related to pgtable entry print standardization posted earlier.
> 
> https://lore.kernel.org/linux-mm/20260831054331.625505-1-anshuman.khandual@arm.com/

This applies.

> 
> https://lore.kernel.org/linux-mm/20260901065454.1906343-1-anshuman.khandual@arm.com/

This fails:
---8<---
$ b4 shazam 20260901065454.1906343-1-anshuman.khandual@arm.com
Grabbing thread from
lore.kernel.org/all/20260901065454.1906343-1-anshuman.khandual@arm.com/t.mbox.gz
Checking for newer revisions
Grabbing search results from lore.kernel.org
  Added from v3: 3 patches
  Added from v2: 3 patches
Analyzing 14 messages in the thread
Looking for additional code-review trailers on lore.kernel.org
Will use the latest revision: v3
You can pick other revisions using the -vN flag
Checking attestation on all messages, may take a moment...
---
  ✓ [PATCH v3 1/2] arm64/mm: Move __check_safe_pte_update()
  ✓ [PATCH v3 2/2] arm64/mm: Standardize printing for pgtable entries
  ---
  ✓ Signed: DKIM/arm.com
---
Total patches: 2
---
Applying: arm64/mm: Move __check_safe_pte_update()
Applying: arm64/mm: Standardize printing for pgtable entries
Patch failed at 0002 arm64/mm: Standardize printing for pgtable entries
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
error: patch failed: arch/arm64/mm/fault.c:160
error: arch/arm64/mm/fault.c: patch does not apply
hint: Use 'git am --show-current-patch=diff' to see the failed patch
---8<---

And as a result I can't apply this series. Any tips?

Thanks,
Ryan


> 
> 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: Convert READ_ONCE() as pmdp_get() while accessing PMD
>   arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD
>   arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D
>   arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD
> 
>  arch/arm64/include/asm/pgtable.h |  6 ++--
>  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, 66 insertions(+), 64 deletions(-)
>