+ arm64-mm-implement-the-architecture-specific-clear_flush_young_ptes.patch added to mm-unstable branch

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

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

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

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------------------------------------------------------
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: arm64: mm: implement the architecture-specific clear_flush_young_ptes()
Date: Mon, 9 Feb 2026 22:07:27 +0800

Implement the Arm64 architecture-specific clear_flush_young_ptes() to
enable batched checking of young flags and TLB flushing, improving
performance during large folio reclamation.

Performance testing:
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 33% performance improvement on my Arm64 32-core server (and
10%+ improvement on my X86 machine).  Meanwhile, the hotspot
folio_check_references() dropped from approximately 35% to around 5%.

W/o patchset:
real	0m1.518s
user	0m0.000s
sys	0m1.518s

W/ patchset:
real	0m1.018s
user	0m0.000s
sys	0m1.018s

Link: https://lkml.kernel.org/r/ce749fbae3e900e733fa104a16fcb3ca9fe4f9bd.1770645603.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
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: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/include/asm/pgtable.h |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/arch/arm64/include/asm/pgtable.h~arm64-mm-implement-the-architecture-specific-clear_flush_young_ptes
+++ a/arch/arm64/include/asm/pgtable.h
@@ -1838,6 +1838,17 @@ static inline int ptep_clear_flush_young
 	return contpte_clear_flush_young_ptes(vma, addr, ptep, 1);
 }
 
+#define clear_flush_young_ptes clear_flush_young_ptes
+static inline int clear_flush_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_clear_flush_young(vma, addr, ptep);
+
+	return contpte_clear_flush_young_ptes(vma, addr, ptep, nr);
+}
+
 #define wrprotect_ptes wrprotect_ptes
 static __always_inline void wrprotect_ptes(struct mm_struct *mm,
 				unsigned long addr, pte_t *ptep, unsigned int nr)
_

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

mm-rmap-support-batched-checks-of-the-references-for-large-folios.patch
arm64-mm-factor-out-the-address-and-ptep-alignment-into-a-new-helper.patch
arm64-mm-support-batch-clearing-of-the-young-flag-for-large-folios.patch
arm64-mm-implement-the-architecture-specific-clear_flush_young_ptes.patch
mm-rmap-support-batched-unmapping-for-file-large-folios.patch