diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 578212fbf2be9b4321b32bc40f7d74da14f687f9..11b874f212a20dcf24e80595624ba355a04e2b66 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -8,6 +8,10 @@
#ifdef CONFIG_MMU
+#ifdef CONFIG_SWAP
+#include <linux/swapfile.h>
+#endif /* CONFIG_SWAP */
+
/*
* swapcache pages are stored in the swapper_space radix tree. We want to
* get good packing density in that tree, so the index should be dense in
@@ -35,6 +39,31 @@
#endif /* MAX_PHYSMEM_BITS */
#define SWP_PFN_MASK (BIT(SWP_PFN_BITS) - 1)
+/**
+ * Migration swap entry specific bitfield definitions. Layout:
+ *
+ * |----------+--------------------|
+ * | swp_type | swp_offset |
+ * |----------+--------+-+-+-------|
+ * | | resv |D|A| PFN |
+ * |----------+--------+-+-+-------|
+ *
+ * @SWP_MIG_YOUNG_BIT: Whether the page used to have young bit set (bit A)
+ * @SWP_MIG_DIRTY_BIT: Whether the page used to have dirty bit set (bit D)
+ *
+ * Note: A/D bits will be stored in migration entries iff there're enough
+ * free bits in arch specific swp offset. By default we'll ignore A/D bits
+ * when migrating a page. Please refer to migration_entry_supports_ad()
+ * for more information. If there're more bits besides PFN and A/D bits,
+ * they should be reserved and always be zeros.
+ */
+#define SWP_MIG_YOUNG_BIT (SWP_PFN_BITS)
+#define SWP_MIG_DIRTY_BIT (SWP_PFN_BITS + 1)
+#define SWP_MIG_TOTAL_BITS (SWP_PFN_BITS + 2)
+
+#define SWP_MIG_YOUNG BIT(SWP_MIG_YOUNG_BIT)
+#define SWP_MIG_DIRTY BIT(SWP_MIG_DIRTY_BIT)
+
static inline bool is_pfn_swap_entry(swp_entry_t entry);
/* Clear all flags but only keep swp_entry_t related information */
@@ -265,6 +294,57 @@ static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
return swp_entry(SWP_MIGRATION_WRITE, offset);
}
+/*
+ * Returns whether the host has large enough swap offset field to support
+ * carrying over pgtable A/D bits for page migrations. The result is
+ * pretty much arch specific.
+ */
+static inline bool migration_entry_supports_ad(void)
+{
+ /*
+ * max_swapfile_size() returns the max supported swp-offset plus 1.
+ * We can support the migration A/D bits iff the pfn swap entry has
+ * the offset large enough to cover all of them (PFN, A & D bits).
+ */
+#ifdef CONFIG_SWAP
+ return max_swapfile_size() >= (1UL << SWP_MIG_TOTAL_BITS);
+#else /* CONFIG_SWAP */
+ return false;
+#endif /* CONFIG_SWAP */
+}
+
+static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
+{
+ if (migration_entry_supports_ad())
+ return swp_entry(swp_type(entry),
+ swp_offset(entry) | SWP_MIG_YOUNG);
+ return entry;
+}
+
+static inline bool is_migration_entry_young(swp_entry_t entry)
+{
+ if (migration_entry_supports_ad())
+ return swp_offset(entry) & SWP_MIG_YOUNG;
+ /* Keep the old behavior of aging page after migration */
+ return false;
+}
+
+static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
+{
+ if (migration_entry_supports_ad())
+ return swp_entry(swp_type(entry),
+ swp_offset(entry) | SWP_MIG_DIRTY);
+ return entry;
+}
+
+static inline bool is_migration_entry_dirty(swp_entry_t entry)
+{
+ if (migration_entry_supports_ad())
+ return swp_offset(entry) & SWP_MIG_DIRTY;
+ /* Keep the old behavior of clean page after migration */
+ return false;
+}
+
extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
spinlock_t *ptl);
extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
@@ -311,6 +391,25 @@ static inline int is_readable_migration_entry(swp_entry_t entry)
return 0;
}
+static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
+{
+ return entry;
+}
+
+static inline bool is_migration_entry_young(swp_entry_t entry)
+{
+ return false;
+}
+
+static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
+{
+ return entry;
+}
+
+static inline bool is_migration_entry_dirty(swp_entry_t entry)
+{
+ return false;
+}
#endif /* CONFIG_MIGRATION */
typedef unsigned long pte_marker;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b4666774abf08da3289eb3c7df39f8abfce4c278..f4a656b279b1b0f49280bd3cce1962052351a0e6 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2121,7 +2121,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
write = is_writable_migration_entry(entry);
if (PageAnon(page))
anon_exclusive = is_readable_exclusive_migration_entry(entry);
- young = false;
+ young = is_migration_entry_young(entry);
+ dirty = is_migration_entry_dirty(entry);
soft_dirty = pmd_swp_soft_dirty(old_pmd);
uffd_wp = pmd_swp_uffd_wp(old_pmd);
} else {
@@ -2183,6 +2184,10 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
else
swp_entry = make_readable_migration_entry(
page_to_pfn(page + i));
+ if (young)
+ swp_entry = make_migration_entry_young(swp_entry);
+ if (dirty)
+ swp_entry = make_migration_entry_dirty(swp_entry);
entry = swp_entry_to_pte(swp_entry);
if (soft_dirty)
entry = pte_swp_mksoft_dirty(entry);
@@ -3201,6 +3206,10 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
entry = make_readable_exclusive_migration_entry(page_to_pfn(page));
else
entry = make_readable_migration_entry(page_to_pfn(page));
+ if (pmd_young(pmdval))
+ entry = make_migration_entry_young(entry);
+ if (pmd_dirty(pmdval))
+ entry = make_migration_entry_dirty(entry);
pmdswp = swp_entry_to_pmd(entry);
if (pmd_soft_dirty(pmdval))
pmdswp = pmd_swp_mksoft_dirty(pmdswp);
@@ -3226,13 +3235,18 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
entry = pmd_to_swp_entry(*pvmw->pmd);
get_page(new);
- pmde = pmd_mkold(mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)));
+ pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
if (pmd_swp_soft_dirty(*pvmw->pmd))
pmde = pmd_mksoft_dirty(pmde);
if (is_writable_migration_entry(entry))
pmde = maybe_pmd_mkwrite(pmde, vma);
if (pmd_swp_uffd_wp(*pvmw->pmd))
pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
+ if (!is_migration_entry_young(entry))
+ pmde = pmd_mkold(pmde);
+ /* NOTE: this may contain setting soft-dirty on some archs */
+ if (PageDirty(new) && is_migration_entry_dirty(entry))
+ pmde = pmd_mkdirty(pmde);
if (PageAnon(new)) {
rmap_t rmap_flags = RMAP_COMPOUND;
diff --git a/mm/migrate.c b/mm/migrate.c
index ce6a58f3b21f11262b0cfe050cf499425cfe38ba..a35eba462e61f51e85679bda604a61315642aa95 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -198,7 +198,7 @@ static bool remove_migration_pte(struct folio *folio,
#endif
folio_get(folio);
- pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
+ pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
if (pte_swp_soft_dirty(*pvmw.pte))
pte = pte_mksoft_dirty(pte);
@@ -206,6 +206,10 @@ static bool remove_migration_pte(struct folio *folio,
* Recheck VMA as permissions can change since migration started
*/
entry = pte_to_swp_entry(*pvmw.pte);
+ if (!is_migration_entry_young(entry))
+ pte = pte_mkold(pte);
+ if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
+ pte = pte_mkdirty(pte);
if (is_writable_migration_entry(entry))
pte = maybe_mkwrite(pte, vma);
else if (pte_swp_uffd_wp(*pvmw.pte))
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index d8efd5a0eb405daa2a85de5abed7639813f6cd15..5ab6ab9d2ed82be3a231e31746571f0c98eeee92 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -233,6 +233,12 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
else
entry = make_readable_migration_entry(
page_to_pfn(page));
+ if (pte_present(pte)) {
+ if (pte_young(pte))
+ entry = make_migration_entry_young(entry);
+ if (pte_dirty(pte))
+ entry = make_migration_entry_dirty(entry);
+ }
swp_pte = swp_entry_to_pte(entry);
if (pte_present(pte)) {
if (pte_soft_dirty(pte))
diff --git a/mm/rmap.c b/mm/rmap.c
index 6781f693df50947debc35bfd6038f234d7c6c97c..131def40e4f0207015fa7a74da9d54926078206e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2066,7 +2066,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
else
entry = make_readable_migration_entry(
page_to_pfn(subpage));
-
+ if (pte_young(pteval))
+ entry = make_migration_entry_young(entry);
+ if (pte_dirty(pteval))
+ entry = make_migration_entry_dirty(entry);
swp_pte = swp_entry_to_pte(entry);
if (pte_soft_dirty(pteval))
swp_pte = pte_swp_mksoft_dirty(swp_pte);