+ mm-extract-non-swap-page-handling-to-do_non_swap_page.patch added to mm-new branch

The patch titled
     Subject: mm: extract non-swap page handling to do_non_swap_page()
has been added to the -mm mm-new branch.  Its filename is
     mm-extract-non-swap-page-handling-to-do_non_swap_page.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-extract-non-swap-page-handling-to-do_non_swap_page.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: Hongfu Li <[email protected]>
Subject: mm: extract non-swap page handling to do_non_swap_page()
Date: Thu, 23 Jul 2026 11:07:52 +0800

Factor non-swap entry logic out of bloated do_swap_page() to simplify the
main swap fault flow and improve readability.

The new do_non_swap_page() handles migration, device private/exclusive,
hwpoison, marker and bad PTE entries.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Hongfu Li <[email protected]>
Cc: David Hildenbrand (Arm) <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/memory.c |  120 ++++++++++++++++++++++++++++----------------------
 1 file changed, 69 insertions(+), 51 deletions(-)

--- a/mm/memory.c~mm-extract-non-swap-page-handling-to-do_non_swap_page
+++ a/mm/memory.c
@@ -4866,6 +4866,74 @@ static void check_swap_exclusive(struct
 	} while (--nr_pages);
 }
 
+static vm_fault_t do_non_swap_page(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct folio *folio;
+	softleaf_t entry;
+	vm_fault_t ret = 0;
+
+	entry = softleaf_from_pte(vmf->orig_pte);
+	if (softleaf_is_migration(entry)) {
+		migration_entry_wait(vma->vm_mm, vmf->pmd,
+				     vmf->address);
+	} else if (softleaf_is_device_exclusive(entry)) {
+		vmf->page = softleaf_to_page(entry);
+		ret = remove_device_exclusive_entry(vmf);
+	} else if (softleaf_is_device_private(entry)) {
+
+		if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+			/*
+			 * migrate_to_ram is not yet ready to operate
+			 * under VMA lock.
+			 */
+			vma_end_read(vma);
+			return VM_FAULT_RETRY;
+		}
+
+		vmf->page = softleaf_to_page(entry);
+		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+						vmf->address, &vmf->ptl);
+		if (unlikely(!vmf->pte ||
+			     !pte_same(ptep_get(vmf->pte),
+					vmf->orig_pte)))
+			goto unlock;
+
+		/*
+		 * Get a folio reference while we know the folio can't be
+		 * freed.
+		 */
+		folio = page_folio(vmf->page);
+		if (folio_trylock(folio)) {
+			struct dev_pagemap *pgmap;
+
+			folio_get(folio);
+			pte_unmap_unlock(vmf->pte, vmf->ptl);
+			pgmap = page_pgmap(vmf->page);
+			ret = pgmap->ops->migrate_to_ram(vmf);
+			folio_unlock(folio);
+			folio_put(folio);
+		} else {
+			pte_unmap(vmf->pte);
+			softleaf_entry_wait_on_locked(entry, vmf->ptl);
+		}
+	} else if (softleaf_is_hwpoison(entry)) {
+		ret = VM_FAULT_HWPOISON;
+	} else if (softleaf_is_marker(entry)) {
+		ret = handle_pte_marker(vmf);
+	} else {
+		print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
+		ret = VM_FAULT_SIGBUS;
+	}
+
+	return ret;
+
+unlock:
+	if (vmf->pte)
+		pte_unmap_unlock(vmf->pte, vmf->ptl);
+	return ret;
+}
+
 /*
  * We enter with either the VMA lock or the mmap_lock held (see
  * FAULT_FLAG_VMA_LOCK), and pte mapped but not yet locked.
@@ -4896,57 +4964,7 @@ vm_fault_t do_swap_page(struct vm_fault
 
 	entry = softleaf_from_pte(vmf->orig_pte);
 	if (unlikely(!softleaf_is_swap(entry))) {
-		if (softleaf_is_migration(entry)) {
-			migration_entry_wait(vma->vm_mm, vmf->pmd,
-					     vmf->address);
-		} else if (softleaf_is_device_exclusive(entry)) {
-			vmf->page = softleaf_to_page(entry);
-			ret = remove_device_exclusive_entry(vmf);
-		} else if (softleaf_is_device_private(entry)) {
-			if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
-				/*
-				 * migrate_to_ram is not yet ready to operate
-				 * under VMA lock.
-				 */
-				vma_end_read(vma);
-				ret = VM_FAULT_RETRY;
-				goto out;
-			}
-
-			vmf->page = softleaf_to_page(entry);
-			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
-					vmf->address, &vmf->ptl);
-			if (unlikely(!vmf->pte ||
-				     !pte_same(ptep_get(vmf->pte),
-							vmf->orig_pte)))
-				goto unlock;
-
-			/*
-			 * Get a folio reference while we know the folio can't be
-			 * freed.
-			 */
-			folio = page_folio(vmf->page);
-			if (folio_trylock(folio)) {
-				struct dev_pagemap *pgmap;
-
-				folio_get(folio);
-				pte_unmap_unlock(vmf->pte, vmf->ptl);
-				pgmap = page_pgmap(vmf->page);
-				ret = pgmap->ops->migrate_to_ram(vmf);
-				folio_unlock(folio);
-				folio_put(folio);
-			} else {
-				pte_unmap(vmf->pte);
-				softleaf_entry_wait_on_locked(entry, vmf->ptl);
-			}
-		} else if (softleaf_is_hwpoison(entry)) {
-			ret = VM_FAULT_HWPOISON;
-		} else if (softleaf_is_marker(entry)) {
-			ret = handle_pte_marker(vmf);
-		} else {
-			print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
-			ret = VM_FAULT_SIGBUS;
-		}
+		ret = do_non_swap_page(vmf);
 		goto out;
 	}
 
_

Patches currently in -mm which might be from [email protected] are

selftests-mm-move-pkey-selftest-helpers-to-pkey_utilc.patch
selftests-mm-unify-pkey-sighandler-selftest-assertions-and-tracing.patch
selftests-mm-use-pkey_assert-on-clone_raw-failure-in-pkey-test.patch
selftests-mm-add-missing-mmap-return-checks-in-pkey-tests.patch
selftests-mm-add-missing-pthread_create-return-checks-in-pkey-tests.patch
selftests-mm-fix-clone-cleartid-race-in-pkey-sighandler-tests.patch
selftests-mm-fix-memleak-in-migration-benchmark.patch
selftests-mm-factor-out-hmm_buffer_alloc-to-consolidate-buffer-setup.patch
selftests-mm-fix-bug_on-checking-wrong-variable-in-mremap_dontunmap.patch
mm-swap-fix-swap_cluster_lock-config_swap-stub-signature-mismatch.patch
mm-use-a-folio-in-the-softleaf_is_device_private-path.patch
mm-extract-non-swap-page-handling-to-do_non_swap_page.patch