+ mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous.patch added to mm-unstable branch

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

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The patch titled
     Subject: mm/rmap: track whether the page VMA mapped pgoff is anonymous
has been added to the -mm mm-unstable branch.  Its filename is
     mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous.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: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: mm/rmap: track whether the page VMA mapped pgoff is anonymous
Date: Thu, 13 Aug 2026 18:32:27 +0100

Update the page_vma_mapped_walk structure to track whether the pgoff being
tracked is an anonymous pgoff or not and update the comments to reflect
this.

This is necessary in order to determine the correct VMA page offset in
vma_address_end() when pvmw->nr_pages > 1.

Also document that pvmw->pgoff is meaningless for pvmw->nr_pages == 1 and
for KSM.

Do not set this field where pgoff is not specified.

This is laying the groundwork for eventually using anonymous page offsets
as the index for all anonymous folios.

No functional change intended.

Link: https://lore.kernel.org/20260813-b4-scalable-cow-virt-pgoff-v5-10-c21581c0c3c8@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cc: Jiri Olsa <jolsa@kernel.org>
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Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/rmap.h |    4 +++-
 mm/rmap.c            |    2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

--- a/include/linux/rmap.h~mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous
+++ a/include/linux/rmap.h
@@ -864,13 +864,14 @@ struct page *make_device_exclusive(struc
 struct page_vma_mapped_walk {
 	unsigned long pfn;
 	unsigned long nr_pages;
-	pgoff_t pgoff;
+	pgoff_t pgoff;	/* Only meaningful if nr_pages > 1 and not a KSM walk */
 	struct vm_area_struct *vma;
 	unsigned long address;
 	pmd_t *pmd;
 	pte_t *pte;
 	spinlock_t *ptl;
 	unsigned int flags;
+	bool pgoff_is_anon : 1;
 };
 
 #define DEFINE_FOLIO_VMA_WALK(name, _folio, _vma, _address, _flags)	\
@@ -881,6 +882,7 @@ struct page_vma_mapped_walk {
 		.vma = _vma,						\
 		.address = _address,					\
 		.flags = _flags,					\
+		.pgoff_is_anon = folio_test_anon(_folio),		\
 	}
 
 static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
--- a/mm/rmap.c~mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous
+++ a/mm/rmap.c
@@ -1240,6 +1240,7 @@ static bool mapping_wrprotect_range_one(
 		.vma		= vma,
 		.address	= address,
 		.flags		= PVMW_SYNC,
+		.pgoff_is_anon	= false,
 	};
 
 	state->cleaned += page_vma_mkclean_one(&pvmw);
@@ -1317,6 +1318,7 @@ int pfn_mkclean_range(unsigned long pfn,
 		.pgoff		= pgoff,
 		.vma		= vma,
 		.flags		= PVMW_SYNC,
+		.pgoff_is_anon	= false,
 	};
 
 	if (invalid_mkclean_vma(vma, NULL))
_

Patches currently in -mm which might be from ljs@kernel.org are

mm-vma-introduce-vma-anon-page-offset-field-and-add-helpers.patch
mm-provide-vma_is_cow_mapping-and-remove-is_cow_mapping.patch
mm-introduce-linear_anon_page_index.patch
mm-abstract-vma_address-and-introduce-vma_anon_address.patch
mm-update-print_bad_page_map-to-show-anon-index-if-appropriate.patch
mm-introduce-and-use-vma_filebacked_address.patch
mm-vma-fix-self-merge-check-in-copy_vma.patch
tools-testing-vma-add-tests-for-copy_vma-self-merge.patch
mm-propagate-vma-anonymous-page-offset-on-map-remap-split-merge.patch
mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous.patch
mm-clean-up-vma_address_end.patch
mm-huge_memory-update-remove_migration_pmd-to-accept-a-folio.patch
mm-migrate-calculate-large-folio-page-index-using-pfn.patch
mm-rmap-use-anon-pgoff-to-track-map_private-file-backed-anon-folios.patch
tools-testing-vma-expand-vma-merge-tests-to-assert-anon-pgoff.patch
tools-testing-selftests-mm-test-anonymous-page-offset-merge-behaviour.patch
mm-add-some-missing-includes-to-mm-local-headers.patch
maintainers-add-drivers-char-memc-to-mm-misc-memory-mapping-sections.patch