[merged mm-stable] mm-add-batched-versions-of-ptep_modify_prot_start-commit.patch removed from -mm tree

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

The quilt patch titled
     Subject: mm: add batched versions of ptep_modify_prot_start/commit
has been removed from the -mm tree.  Its filename was
     mm-add-batched-versions-of-ptep_modify_prot_start-commit.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Dev Jain <dev.jain@arm.com>
Subject: mm: add batched versions of ptep_modify_prot_start/commit
Date: Fri, 18 Jul 2025 14:32:40 +0530

Batch ptep_modify_prot_start/commit in preparation for optimizing
mprotect, implementing them as a simple loop over the corresponding single
pte helpers.  Architecture may override these helpers.

Link: https://lkml.kernel.org/r/20250718090244.21092-4-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/pgtable.h |   84 +++++++++++++++++++++++++++++++++++++-
 mm/mprotect.c           |    4 -
 2 files changed, 85 insertions(+), 3 deletions(-)

--- a/include/linux/pgtable.h~mm-add-batched-versions-of-ptep_modify_prot_start-commit
+++ a/include/linux/pgtable.h
@@ -1331,7 +1331,9 @@ static inline pte_t ptep_modify_prot_sta
 
 /*
  * Commit an update to a pte, leaving any hardware-controlled bits in
- * the PTE unmodified.
+ * the PTE unmodified. The pte returned from ptep_modify_prot_start() may
+ * additionally have young and/or dirty bits set where previously they were not,
+ * so the updated pte may have these additional changes.
  */
 static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
 					   unsigned long addr,
@@ -1340,6 +1342,86 @@ static inline void ptep_modify_prot_comm
 	__ptep_modify_prot_commit(vma, addr, ptep, pte);
 }
 #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
+
+/**
+ * modify_prot_start_ptes - Start a pte protection read-modify-write transaction
+ * over a batch of ptes, which protects against asynchronous hardware
+ * modifications to the ptes. The intention is not to prevent the hardware from
+ * making pte updates, but to prevent any updates it may make from being lost.
+ * Please see the comment above ptep_modify_prot_start() for full description.
+ *
+ * @vma: The virtual memory area the pages are mapped into.
+ * @addr: Address the first page is mapped at.
+ * @ptep: Page table pointer for the first entry.
+ * @nr: Number of entries.
+ *
+ * May be overridden by the architecture; otherwise, implemented as a simple
+ * loop over ptep_modify_prot_start(), collecting the a/d bits from each pte
+ * in the batch.
+ *
+ * Note that PTE bits in the PTE batch besides the PFN can differ.
+ *
+ * Context: The caller holds the page table lock.  The PTEs map consecutive
+ * pages that belong to the same folio. All other PTE bits must be identical for
+ * all PTEs in the batch except for young and dirty bits.  The PTEs are all in
+ * the same PMD.
+ */
+#ifndef modify_prot_start_ptes
+static inline pte_t modify_prot_start_ptes(struct vm_area_struct *vma,
+		unsigned long addr, pte_t *ptep, unsigned int nr)
+{
+	pte_t pte, tmp_pte;
+
+	pte = ptep_modify_prot_start(vma, addr, ptep);
+	while (--nr) {
+		ptep++;
+		addr += PAGE_SIZE;
+		tmp_pte = ptep_modify_prot_start(vma, addr, ptep);
+		if (pte_dirty(tmp_pte))
+			pte = pte_mkdirty(pte);
+		if (pte_young(tmp_pte))
+			pte = pte_mkyoung(pte);
+	}
+	return pte;
+}
+#endif
+
+/**
+ * modify_prot_commit_ptes - Commit an update to a batch of ptes, leaving any
+ * hardware-controlled bits in the PTE unmodified.
+ *
+ * @vma: The virtual memory area the pages are mapped into.
+ * @addr: Address the first page is mapped at.
+ * @ptep: Page table pointer for the first entry.
+ * @old_pte: Old page table entry (for the first entry) which is now cleared.
+ * @pte: New page table entry to be set.
+ * @nr: Number of entries.
+ *
+ * May be overridden by the architecture; otherwise, implemented as a simple
+ * loop over ptep_modify_prot_commit().
+ *
+ * Context: The caller holds the page table lock. The PTEs are all in the same
+ * PMD. On exit, the set ptes in the batch map the same folio. The ptes set by
+ * ptep_modify_prot_start() may additionally have young and/or dirty bits set
+ * where previously they were not, so the updated ptes may have these
+ * additional changes.
+ */
+#ifndef modify_prot_commit_ptes
+static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
+		pte_t *ptep, pte_t old_pte, pte_t pte, unsigned int nr)
+{
+	int i;
+
+	for (i = 0; i < nr; ++i, ++ptep, addr += PAGE_SIZE) {
+		ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte);
+
+		/* Advance PFN only, set same prot */
+		old_pte = pte_next_pfn(old_pte);
+		pte = pte_next_pfn(pte);
+	}
+}
+#endif
+
 #endif /* CONFIG_MMU */
 
 /*
--- a/mm/mprotect.c~mm-add-batched-versions-of-ptep_modify_prot_start-commit
+++ a/mm/mprotect.c
@@ -204,7 +204,7 @@ static long change_pte_range(struct mmu_
 				}
 			}
 
-			oldpte = ptep_modify_prot_start(vma, addr, pte);
+			oldpte = modify_prot_start_ptes(vma, addr, pte, nr_ptes);
 			ptent = pte_modify(oldpte, newprot);
 
 			if (uffd_wp)
@@ -230,7 +230,7 @@ static long change_pte_range(struct mmu_
 			    can_change_pte_writable(vma, addr, ptent))
 				ptent = pte_mkwrite(ptent, vma);
 
-			ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
+			modify_prot_commit_ptes(vma, addr, pte, oldpte, ptent, nr_ptes);
 			if (pte_needs_flush(oldpte, ptent))
 				tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
 			pages++;
_

Patches currently in -mm which might be from dev.jain@arm.com are

khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching.patch
khugepaged-optimize-collapse_pte_mapped_thp-by-pte-batching.patch