mm/rmap: add anon folio unmap dispatcher

Add ttu_anon_folio() as the common entry point for anonymous folio
unmapping.  It dispatches to the lazyfree or swapbacked helper as
appropriate.

Keep restoration of cleared PTEs in the caller, where the PTEs were
removed.

No functional change intended.

Link: https://lore.kernel.org/20260730094559.418003-6-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
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 (ARM) <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>

1 files changed, 23 insertions, 22 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 15efde4d1fc9..867db2b61573 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2172,6 +2172,26 @@ static bool ttu_anon_swapbacked_folio(struct vm_area_struct *vma,
 	return true;
 }
 
+static bool ttu_anon_folio(struct vm_area_struct *vma, struct folio *folio,
+		struct page *page, unsigned long address, pte_t *ptep,
+		pte_t pteval, unsigned long nr_pages)
+{
+	/*
+	 * Store the swap location in the pte.
+	 * See handle_pte_fault() ...
+	 */
+	if (WARN_ON_ONCE(folio_test_swapbacked(folio) !=
+			 folio_test_swapcache(folio)))
+		return false;
+
+	if (!folio_test_swapbacked(folio))
+		return ttu_anon_lazyfree_folio(vma, folio, nr_pages);
+
+	/* nr_pages > 1 not supported yet */
+	return ttu_anon_swapbacked_folio(vma, folio, page, address, ptep,
+					 pteval);
+}
+
 /*
  * @arg: enum ttu_flags will be passed to this argument
  */
@@ -2349,31 +2369,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 */
 			dec_mm_counter(mm, mm_counter(folio));
 		} else if (folio_test_anon(folio)) {
-			/*
-			 * Store the swap location in the pte.
-			 * See handle_pte_fault() ...
-			 */
-			if (unlikely(folio_test_swapbacked(folio) !=
-					folio_test_swapcache(folio))) {
-				WARN_ON_ONCE(1);
+			if (!ttu_anon_folio(vma, folio, page, address,
+					    pvmw.pte, pteval, nr_pages)) {
+				set_ptes(mm, address, pvmw.pte, pteval, nr_pages);
 				goto walk_abort;
 			}
 
-			/* MADV_FREE page check */
-			if (!folio_test_swapbacked(folio)) {
-				if (!ttu_anon_lazyfree_folio(vma, folio,
-							     nr_pages)) {
-					set_ptes(mm, address, pvmw.pte, pteval, nr_pages);
-					goto walk_abort;
-				}
-				goto finish_unmap;
-			}
-
-			if (!ttu_anon_swapbacked_folio(vma, folio, page, address,
-						pvmw.pte, pteval)) {
-				set_pte_at(mm, address, pvmw.pte, pteval);
-				goto walk_abort;
-			}
 			goto finish_unmap;
 		} else {
 			/*