diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index d3bbf6bea9e9..213d32e57c39 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -80,6 +80,11 @@ extern struct kobj_attribute shmem_enabled_attr;
 #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
 
+static inline bool thp_swap_supported(void)
+{
+	return IS_ENABLED(CONFIG_THP_SWAP);
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define HPAGE_PMD_SHIFT PMD_SHIFT
 #define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index f73eafcaf4e9..57aa655ab27d 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -451,8 +451,8 @@ extern swp_entry_t get_swap_page_of_type(int);
 extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 extern void swap_shmem_alloc(swp_entry_t);
-extern int swap_duplicate(swp_entry_t);
-extern int swapcache_prepare(swp_entry_t);
+extern int swap_duplicate(swp_entry_t *entry, bool cluster);
+extern int swapcache_prepare(swp_entry_t entry, bool cluster);
 extern void swap_free(swp_entry_t);
 extern void swapcache_free_entries(swp_entry_t *entries, int n);
 extern int free_swap_and_cache(swp_entry_t);
@@ -510,7 +510,8 @@ static inline void show_swap_cache_info(void)
 }
 
 #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
-#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
+#define swapcache_prepare(e, c)						\
+	({(is_migration_entry(e) || is_device_private_entry(e)); })
 
 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 {
@@ -521,7 +522,7 @@ static inline void swap_shmem_alloc(swp_entry_t swp)
 {
 }
 
-static inline int swap_duplicate(swp_entry_t swp)
+static inline int swap_duplicate(swp_entry_t *swp, bool cluster)
 {
 	return 0;
 }
diff --git a/mm/memory.c b/mm/memory.c
index e9cac1c4fa69..f3900282e3da 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -951,7 +951,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		swp_entry_t entry = pte_to_swp_entry(pte);
 
 		if (likely(!non_swap_entry(entry))) {
-			if (swap_duplicate(entry) < 0)
+			if (swap_duplicate(&entry, false) < 0)
 				return entry.val;
 
 			/* make sure dst_mm is on swapoff's mmlist. */
diff --git a/mm/rmap.c b/mm/rmap.c
index 6db729dc4c50..5f45d6325c40 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1556,7 +1556,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				break;
 			}
 
-			if (swap_duplicate(entry) < 0) {
+			if (swap_duplicate(&entry, false) < 0) {
 				set_pte_at(mm, address, pvmw.pte, pteval);
 				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index dc312559f7df..b0575182e77b 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -433,7 +433,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		/*
 		 * Swap entry may have been freed since our caller observed it.
 		 */
-		err = swapcache_prepare(entry);
+		err = swapcache_prepare(entry, false);
 		if (err == -EEXIST) {
 			radix_tree_preload_end();
 			/*
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f42b1b0cdc58..48e2c54385ee 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -49,6 +49,9 @@ static bool swap_count_continued(struct swap_info_struct *, pgoff_t,
 				 unsigned char);
 static void free_swap_count_continuations(struct swap_info_struct *);
 static sector_t map_swap_entry(swp_entry_t, struct block_device**);
+static int add_swap_count_continuation_locked(struct swap_info_struct *si,
+					      unsigned long offset,
+					      struct page *page);
 
 DEFINE_SPINLOCK(swap_lock);
 static unsigned int nr_swapfiles;
@@ -319,6 +322,11 @@ static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si,
 		spin_unlock(&si->lock);
 }
 
+static inline bool is_cluster_offset(unsigned long offset)
+{
+	return !(offset % SWAPFILE_CLUSTER);
+}
+
 static inline bool cluster_list_empty(struct swap_cluster_list *list)
 {
 	return cluster_is_null(&list->head);
@@ -1166,16 +1174,14 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry)
 	return NULL;
 }
 
-static unsigned char __swap_entry_free(struct swap_info_struct *p,
-				       swp_entry_t entry, unsigned char usage)
+static unsigned char __swap_entry_free_locked(struct swap_info_struct *p,
+					      struct swap_cluster_info *ci,
+					      unsigned long offset,
+					      unsigned char usage)
 {
-	struct swap_cluster_info *ci;
-	unsigned long offset = swp_offset(entry);
 	unsigned char count;
 	unsigned char has_cache;
 
-	ci = lock_cluster_or_swap_info(p, offset);
-
 	count = p->swap_map[offset];
 
 	has_cache = count & SWAP_HAS_CACHE;
@@ -1203,6 +1209,17 @@ static unsigned char __swap_entry_free(struct swap_info_struct *p,
 	usage = count | has_cache;
 	p->swap_map[offset] = usage ? : SWAP_HAS_CACHE;
 
+	return usage;
+}
+
+static unsigned char __swap_entry_free(struct swap_info_struct *p,
+				       swp_entry_t entry, unsigned char usage)
+{
+	struct swap_cluster_info *ci;
+	unsigned long offset = swp_offset(entry);
+
+	ci = lock_cluster_or_swap_info(p, offset);
+	usage = __swap_entry_free_locked(p, ci, offset, usage);
 	unlock_cluster_or_swap_info(p, ci);
 
 	return usage;
@@ -3450,32 +3467,12 @@ void si_swapinfo(struct sysinfo *val)
 	spin_unlock(&swap_lock);
 }
 
-/*
- * Verify that a swap entry is valid and increment its swap map count.
- *
- * Returns error code in following case.
- * - success -> 0
- * - swp_entry is invalid -> EINVAL
- * - swp_entry is migration entry -> EINVAL
- * - swap-cache reference is requested but there is already one. -> EEXIST
- * - swap-cache reference is requested but the entry is not used. -> ENOENT
- * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
- */
-static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
+static int __swap_duplicate_locked(struct swap_info_struct *p,
+				   unsigned long offset, unsigned char usage)
 {
-	struct swap_info_struct *p;
-	struct swap_cluster_info *ci;
-	unsigned long offset;
 	unsigned char count;
 	unsigned char has_cache;
-	int err = -EINVAL;
-
-	p = get_swap_device(entry);
-	if (!p)
-		goto out;
-
-	offset = swp_offset(entry);
-	ci = lock_cluster_or_swap_info(p, offset);
+	int err = 0;
 
 	count = p->swap_map[offset];
 
@@ -3485,12 +3482,11 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
 	 */
 	if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
 		err = -ENOENT;
-		goto unlock_out;
+		goto out;
 	}
 
 	has_cache = count & SWAP_HAS_CACHE;
 	count &= ~SWAP_HAS_CACHE;
-	err = 0;
 
 	if (usage == SWAP_HAS_CACHE) {
 
@@ -3517,11 +3513,39 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
 
 	p->swap_map[offset] = count | has_cache;
 
-unlock_out:
+out:
+	return err;
+}
+
+/*
+ * Verify that a swap entry is valid and increment its swap map count.
+ *
+ * Returns error code in following case.
+ * - success -> 0
+ * - swp_entry is invalid -> EINVAL
+ * - swp_entry is migration entry -> EINVAL
+ * - swap-cache reference is requested but there is already one. -> EEXIST
+ * - swap-cache reference is requested but the entry is not used. -> ENOENT
+ * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
+ */
+static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
+{
+	struct swap_info_struct *p;
+	struct swap_cluster_info *ci;
+	unsigned long offset;
+	int err = -EINVAL;
+
+	p = get_swap_device(entry);
+	if (!p)
+		goto out;
+
+	offset = swp_offset(entry);
+	ci = lock_cluster_or_swap_info(p, offset);
+	err = __swap_duplicate_locked(p, offset, usage);
 	unlock_cluster_or_swap_info(p, ci);
+
+	put_swap_device(p);
 out:
-	if (p)
-		put_swap_device(p);
 	return err;
 }
 
@@ -3534,6 +3558,81 @@ void swap_shmem_alloc(swp_entry_t entry)
 	__swap_duplicate(entry, SWAP_MAP_SHMEM);
 }
 
+#ifdef CONFIG_THP_SWAP
+static int __swap_duplicate_cluster(swp_entry_t *entry, unsigned char usage)
+{
+	struct swap_info_struct *si;
+	struct swap_cluster_info *ci;
+	unsigned long offset;
+	unsigned char *map;
+	int i, err = 0;
+
+	si = get_swap_device(*entry);
+	if (!si) {
+		err = -EINVAL;
+		goto out;
+	}
+	offset = swp_offset(*entry);
+	ci = lock_cluster(si, offset);
+	if (cluster_is_free(ci)) {
+		err = -ENOENT;
+		goto unlock;
+	}
+	if (!cluster_is_huge(ci)) {
+		err = -ENOTDIR;
+		goto unlock;
+	}
+	VM_BUG_ON(!is_cluster_offset(offset));
+	VM_BUG_ON(cluster_count(ci) < SWAPFILE_CLUSTER);
+	map = si->swap_map + offset;
+	if (usage == SWAP_HAS_CACHE) {
+		if (map[0] & SWAP_HAS_CACHE) {
+			err = -EEXIST;
+			goto unlock;
+		}
+		for (i = 0; i < SWAPFILE_CLUSTER; i++) {
+			VM_BUG_ON(map[i] & SWAP_HAS_CACHE);
+			map[i] |= SWAP_HAS_CACHE;
+		}
+	} else {
+		for (i = 0; i < SWAPFILE_CLUSTER; i++) {
+retry:
+			err = __swap_duplicate_locked(si, offset + i, usage);
+			if (err == -ENOMEM) {
+				struct page *page;
+
+				page = alloc_page(GFP_ATOMIC | __GFP_HIGHMEM);
+				err = add_swap_count_continuation_locked(
+					si, offset + i, page);
+				if (err) {
+					*entry = swp_entry(si->type, offset+i);
+					goto undup;
+				}
+				goto retry;
+			} else if (err)
+				goto undup;
+		}
+		cluster_set_count(ci, cluster_count(ci) + usage);
+	}
+unlock:
+	unlock_cluster(ci);
+	put_swap_device(si);
+out:
+	return err;
+undup:
+	for (i--; i >= 0; i--)
+		__swap_entry_free_locked(
+			si, ci, offset + i, usage);
+	goto unlock;
+}
+#else
+static inline int __swap_duplicate_cluster(swp_entry_t *entry,
+					   unsigned char usage)
+{
+	return 0;
+}
+#endif
+
 /*
  * Increase reference count of swap entry by 1.
  * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
@@ -3541,12 +3640,15 @@ void swap_shmem_alloc(swp_entry_t entry)
  * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
  * might occur if a page table entry has got corrupted.
  */
-int swap_duplicate(swp_entry_t entry)
+int swap_duplicate(swp_entry_t *entry, bool cluster)
 {
 	int err = 0;
 
-	while (!err && __swap_duplicate(entry, 1) == -ENOMEM)
-		err = add_swap_count_continuation(entry, GFP_ATOMIC);
+	if (thp_swap_supported() && cluster)
+		return __swap_duplicate_cluster(entry, 1);
+
+	while (!err && __swap_duplicate(*entry, 1) == -ENOMEM)
+		err = add_swap_count_continuation(*entry, GFP_ATOMIC);
 	return err;
 }
 
@@ -3558,9 +3660,12 @@ int swap_duplicate(swp_entry_t entry)
  * -EBUSY means there is a swap cache.
  * Note: return code is different from swap_duplicate().
  */
-int swapcache_prepare(swp_entry_t entry)
+int swapcache_prepare(swp_entry_t entry, bool cluster)
 {
-	return __swap_duplicate(entry, SWAP_HAS_CACHE);
+	if (thp_swap_supported() && cluster)
+		return __swap_duplicate_cluster(&entry, SWAP_HAS_CACHE);
+	else
+		return __swap_duplicate(entry, SWAP_HAS_CACHE);
 }
 
 struct swap_info_struct *swp_swap_info(swp_entry_t entry)
@@ -3590,51 +3695,13 @@ pgoff_t __page_file_index(struct page *page)
 }
 EXPORT_SYMBOL_GPL(__page_file_index);
 
-/*
- * add_swap_count_continuation - called when a swap count is duplicated
- * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
- * page of the original vmalloc'ed swap_map, to hold the continuation count
- * (for that entry and for its neighbouring PAGE_SIZE swap entries).  Called
- * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
- *
- * These continuation pages are seldom referenced: the common paths all work
- * on the original swap_map, only referring to a continuation page when the
- * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
- *
- * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
- * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
- * can be called after dropping locks.
- */
-int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
+static int add_swap_count_continuation_locked(struct swap_info_struct *si,
+					      unsigned long offset,
+					      struct page *page)
 {
-	struct swap_info_struct *si;
-	struct swap_cluster_info *ci;
 	struct page *head;
-	struct page *page;
 	struct page *list_page;
-	pgoff_t offset;
 	unsigned char count;
-	int ret = 0;
-
-	/*
-	 * When debugging, it's easier to use __GFP_ZERO here; but it's better
-	 * for latency not to zero a page while GFP_ATOMIC and holding locks.
-	 */
-	page = alloc_page(gfp_mask | __GFP_HIGHMEM);
-
-	si = get_swap_device(entry);
-	if (!si) {
-		/*
-		 * An acceptable race has occurred since the failing
-		 * __swap_duplicate(): the swap device may be swapoff
-		 */
-		goto outer;
-	}
-	spin_lock(&si->lock);
-
-	offset = swp_offset(entry);
-
-	ci = lock_cluster(si, offset);
 
 	count = si->swap_map[offset] & ~SWAP_HAS_CACHE;
 
@@ -3644,13 +3711,11 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
 		 * will race to add swap count continuation: we need to avoid
 		 * over-provisioning.
 		 */
-		goto out;
+		return 0;
 	}
 
-	if (!page) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!page)
+		return -ENOMEM;
 
 	/*
 	 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
@@ -3698,7 +3763,57 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
 	page = NULL;			/* now it's attached, don't free it */
 out_unlock_cont:
 	spin_unlock(&si->cont_lock);
-out:
+	if (page)
+		__free_page(page);
+	return 0;
+}
+
+/*
+ * add_swap_count_continuation - called when a swap count is duplicated
+ * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
+ * page of the original vmalloc'ed swap_map, to hold the continuation count
+ * (for that entry and for its neighbouring PAGE_SIZE swap entries).  Called
+ * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
+ *
+ * These continuation pages are seldom referenced: the common paths all work
+ * on the original swap_map, only referring to a continuation page when the
+ * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
+ *
+ * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
+ * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
+ * can be called after dropping locks.
+ */
+int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
+{
+	struct swap_info_struct *si;
+	struct swap_cluster_info *ci;
+	struct page *page;
+	unsigned long offset;
+	int ret = 0;
+
+	/*
+	 * When debugging, it's easier to use __GFP_ZERO here; but it's better
+	 * for latency not to zero a page while GFP_ATOMIC and holding locks.
+	 */
+	page = alloc_page(gfp_mask | __GFP_HIGHMEM);
+
+	si = get_swap_device(entry);
+	if (!si) {
+		/*
+		 * An acceptable race has occurred since the failing
+		 * __swap_duplicate(): the swap device may be swapoff
+		 */
+		goto outer;
+	}
+	spin_lock(&si->lock);
+
+	offset = swp_offset(entry);
+
+	ci = lock_cluster(si, offset);
+
+	ret = add_swap_count_continuation_locked(si, offset, page);
+	page = NULL;
+
 	unlock_cluster(ci);
 	spin_unlock(&si->lock);
 	put_swap_device(si);
