+ mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one.patch added to mm-new branch

+ mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/rmap: refactor anon folio unmap in try_to_unmap_one
has been added to the -mm mm-new branch.  Its filename is
     mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one.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

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Dev Jain <dev.jain@arm.com>
Subject: mm/rmap: refactor anon folio unmap in try_to_unmap_one
Date: Mon, 13 Jul 2026 05:00:47 +0000

Refactor anonymous swapbacked folio unmap to ttu_anon_swapbacked_folio(). 
While at it, rename the remaining subpage variables to page; folios have
pages, not subpages.

No functional change intended.

Link: https://lore.kernel.org/20260713050050.1017741-5-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/rmap.c |  115 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 68 insertions(+), 47 deletions(-)

--- a/mm/rmap.c~mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one
+++ a/mm/rmap.c
@@ -2112,6 +2112,66 @@ static bool ttu_anon_lazyfree_folio(stru
 	return true;
 }
 
+static pte_t swp_pte_prepare(swp_entry_t entry, pte_t old_pte,
+		bool anon_exclusive)
+{
+	pte_t swp_pte = swp_entry_to_pte(entry);
+
+	if (anon_exclusive)
+		swp_pte = pte_swp_mkexclusive(swp_pte);
+
+	if (likely(pte_present(old_pte))) {
+		if (pte_soft_dirty(old_pte))
+			swp_pte = pte_swp_mksoft_dirty(swp_pte);
+		if (pte_uffd(old_pte))
+			swp_pte = pte_swp_mkuffd(swp_pte);
+	} else {
+		/* Device-exclusive entry */
+		if (pte_swp_soft_dirty(old_pte))
+			swp_pte = pte_swp_mksoft_dirty(swp_pte);
+		if (pte_swp_uffd(old_pte))
+			swp_pte = pte_swp_mkuffd(swp_pte);
+	}
+
+	return swp_pte;
+}
+
+static bool ttu_anon_swapbacked_folio(struct vm_area_struct *vma,
+		struct folio *folio, struct page *page, unsigned long address,
+		pte_t *ptep, pte_t pteval)
+{
+	const bool anon_exclusive = folio_test_anon(folio) &&
+				    PageAnonExclusive(page);
+	swp_entry_t entry = page_swap_entry(page);
+	struct mm_struct *mm = vma->vm_mm;
+
+	if (folio_dup_swap(folio, page) < 0)
+		return false;
+
+	/*
+	 * arch_unmap_one() is expected to be a NOP on
+	 * architectures where we could have PFN swap PTEs,
+	 * so we'll not check/care.
+	 */
+	if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+		folio_put_swap(folio, page);
+		return false;
+	}
+
+	/* See folio_try_share_anon_rmap(): clear PTE first. */
+	if (anon_exclusive && folio_try_share_anon_rmap_pte(folio, page)) {
+		folio_put_swap(folio, page);
+		return false;
+	}
+
+	mm_prepare_for_swap_entries(mm);
+	dec_mm_counter(mm, MM_ANONPAGES);
+	inc_mm_counter(mm, MM_SWAPENTS);
+	set_pte_at(mm, address, ptep,
+		   swp_pte_prepare(entry, pteval, anon_exclusive));
+	return true;
+}
+
 /*
  * @arg: enum ttu_flags will be passed to this argument
  */
@@ -2120,9 +2180,9 @@ static bool try_to_unmap_one(struct foli
 {
 	struct mm_struct *mm = vma->vm_mm;
 	DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
-	bool anon_exclusive, ret = true;
+	bool ret = true;
 	pte_t pteval;
-	struct page *subpage;
+	struct page *page;
 	struct mmu_notifier_range range;
 	enum ttu_flags flags = (enum ttu_flags)(long)arg;
 	unsigned long nr_pages = 1, end_addr;
@@ -2233,9 +2293,7 @@ static bool try_to_unmap_one(struct foli
 			pfn = softleaf_to_pfn(entry);
 		}
 
-		subpage = folio_page(folio, pfn - folio_pfn(folio));
-		anon_exclusive = folio_test_anon(folio) &&
-				 PageAnonExclusive(subpage);
+		page = folio_page(folio, pfn - folio_pfn(folio));
 
 		if (likely(pte_present(pteval))) {
 			nr_pages = folio_unmap_pte_batch(folio, &pvmw, flags, pteval);
@@ -2274,7 +2332,7 @@ static bool try_to_unmap_one(struct foli
 
 		/* With TTU_HWPOISON, we only expect small folios here. */
 		if (folio_test_hwpoison(folio) && (flags & TTU_HWPOISON)) {
-			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
+			pteval = swp_entry_to_pte(make_hwpoison_entry(page));
 			dec_mm_counter(mm, mm_counter(folio));
 			set_pte_at(mm, address, pvmw.pte, pteval);
 		} else if (likely(pte_present(pteval)) && pte_unused(pteval) &&
@@ -2291,8 +2349,6 @@ static bool try_to_unmap_one(struct foli
 			 */
 			dec_mm_counter(mm, mm_counter(folio));
 		} else if (folio_test_anon(folio)) {
-			swp_entry_t entry = page_swap_entry(subpage);
-			pte_t swp_pte;
 			/*
 			 * Store the swap location in the pte.
 			 * See handle_pte_fault() ...
@@ -2313,47 +2369,12 @@ static bool try_to_unmap_one(struct foli
 				goto finish_unmap;
 			}
 
-			if (folio_dup_swap(folio, subpage) < 0) {
+			if (!ttu_anon_swapbacked_folio(vma, folio, page, address,
+						pvmw.pte, pteval)) {
 				set_pte_at(mm, address, pvmw.pte, pteval);
 				goto walk_abort;
 			}
-
-			/*
-			 * arch_unmap_one() is expected to be a NOP on
-			 * architectures where we could have PFN swap PTEs,
-			 * so we'll not check/care.
-			 */
-			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
-				folio_put_swap(folio, subpage);
-				set_pte_at(mm, address, pvmw.pte, pteval);
-				goto walk_abort;
-			}
-
-			/* See folio_try_share_anon_rmap(): clear PTE first. */
-			if (anon_exclusive &&
-			    folio_try_share_anon_rmap_pte(folio, subpage)) {
-				folio_put_swap(folio, subpage);
-				set_pte_at(mm, address, pvmw.pte, pteval);
-				goto walk_abort;
-			}
-			mm_prepare_for_swap_entries(mm);
-			dec_mm_counter(mm, MM_ANONPAGES);
-			inc_mm_counter(mm, MM_SWAPENTS);
-			swp_pte = swp_entry_to_pte(entry);
-			if (anon_exclusive)
-				swp_pte = pte_swp_mkexclusive(swp_pte);
-			if (likely(pte_present(pteval))) {
-				if (pte_soft_dirty(pteval))
-					swp_pte = pte_swp_mksoft_dirty(swp_pte);
-				if (pte_uffd(pteval))
-					swp_pte = pte_swp_mkuffd(swp_pte);
-			} else {
-				if (pte_swp_soft_dirty(pteval))
-					swp_pte = pte_swp_mksoft_dirty(swp_pte);
-				if (pte_swp_uffd(pteval))
-					swp_pte = pte_swp_mkuffd(swp_pte);
-			}
-			set_pte_at(mm, address, pvmw.pte, swp_pte);
+			goto finish_unmap;
 		} else {
 			/*
 			 * This is a locked file-backed folio,
@@ -2369,7 +2390,7 @@ static bool try_to_unmap_one(struct foli
 			add_mm_counter(mm, mm_counter_file(folio), -nr_pages);
 		}
 finish_unmap:
-		folio_remove_rmap_ptes(folio, subpage, nr_pages, vma);
+		folio_remove_rmap_ptes(folio, page, nr_pages, vma);
 		if (vma->vm_flags & VM_LOCKED)
 			mlock_drain_local();
 		folio_put_refs(folio, nr_pages);
_

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

mm-swap-rename-subpage-page-in-folio_dup_swap-folio_put_swap.patch
mm-mprotect-drop-sub-from-batching-context.patch
arm64-make-huge_ptep_get-handled-unaligned-addresses.patch
mm-rmap-use-huge_ptep_get-in-try_to_unmap_one.patch
mm-rmap-use-huge_ptep_get-in-try_to_migrate_one.patch
mm-migrate-use-huge_ptep_get-in-remove_migration_pte.patch
mm-page_vma_mapped-use-huge_ptep_get-for-hugetlb.patch
mm-mprotect-use-huge_ptep_get-for-hugetlb.patch
mm-rmap-convert-page-folio-for-hwpoison-checks.patch
mm-rmap-add-try_to_unmap_hugetlb_one.patch
mm-rmap-refactor-some-code-around-lazyfree-folio-unmapping.patch
mm-rmap-refactor-anon-folio-unmap-in-try_to_unmap_one.patch
mm-rmap-add-anon-folio-unmap-dispatcher.patch