+ arm64-mm-implement-the-architecture-specific-test_and_clear_young_ptes.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: arm64: mm: implement the architecture-specific test_and_clear_young_ptes()
has been added to the -mm mm-new branch.  Its filename is
     arm64-mm-implement-the-architecture-specific-test_and_clear_young_ptes.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm64-mm-implement-the-architecture-specific-test_and_clear_young_ptes.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

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------------------------------------------------------
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: arm64: mm: implement the architecture-specific test_and_clear_young_ptes()
Date: Fri, 27 Feb 2026 17:44:40 +0800

Implement the Arm64 architecture-specific test_and_clear_young_ptes() to enable
batched checking of young flags, improving performance during large folio
reclamation when MGLRU is enabled.

While we're at it, simplify ptep_test_and_clear_young() by calling
test_and_clear_young_ptes(). Since callers guarantee that PTEs are present
before calling these functions, we can use pte_cont() to check the CONT_PTE
flag instead of pte_valid_cont().

Performance testing:
Enable MGLRU, then allocate 10G clean file-backed folios by mmap() in a memory
cgroup, and try to reclaim 8G file-backed folios via the memory.reclaim interface.
I can observe 60%+ performance improvement on my Arm64 32-core server (and about
15% improvement on my X86 machine).

W/o patchset:
real	0m0.470s
user	0m0.000s
sys	0m0.470s

W/ patchset:
real	0m0.180s
user	0m0.001s
sys	0m0.179s

Link: https://lkml.kernel.org/r/5d9298b94607b2bf4f1f92ea29a4c96217c5bcc1.1772185080.git.baolin.wang@linux.alibaba.com
Reviewed-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/include/asm/pgtable.h |   18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

--- a/arch/arm64/include/asm/pgtable.h~arm64-mm-implement-the-architecture-specific-test_and_clear_young_ptes
+++ a/arch/arm64/include/asm/pgtable.h
@@ -1812,16 +1812,22 @@ static inline pte_t ptep_get_and_clear(s
 	return __ptep_get_and_clear(mm, addr, ptep);
 }
 
+#define test_and_clear_young_ptes test_and_clear_young_ptes
+static inline int test_and_clear_young_ptes(struct vm_area_struct *vma,
+					    unsigned long addr, pte_t *ptep,
+					    unsigned int nr)
+{
+	if (likely(nr == 1 && !pte_cont(__ptep_get(ptep))))
+		return __ptep_test_and_clear_young(vma, addr, ptep);
+
+	return contpte_test_and_clear_young_ptes(vma, addr, ptep, nr);
+}
+
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
 				unsigned long addr, pte_t *ptep)
 {
-	pte_t orig_pte = __ptep_get(ptep);
-
-	if (likely(!pte_valid_cont(orig_pte)))
-		return __ptep_test_and_clear_young(vma, addr, ptep);
-
-	return contpte_test_and_clear_young_ptes(vma, addr, ptep, 1);
+	return test_and_clear_young_ptes(vma, addr, ptep, 1);
 }
 
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
_

Patches currently in -mm which might be from baolin.wang@linux.alibaba.com are

mm-use-inline-helper-functions-instead-of-ugly-macros.patch
mm-rename-ptep-pmdp_clear_young_notify-to-ptep-pmdp_test_and_clear_young_notify.patch
mm-rmap-add-a-zone_device-folio-warning-in-folio_referenced.patch
mm-add-a-batched-helper-to-clear-the-young-flag-for-large-folios.patch
mm-support-batched-checking-of-the-young-flag-for-mglru.patch
arm64-mm-implement-the-architecture-specific-test_and_clear_young_ptes.patch