diff --git a/mm/shmem.c b/mm/shmem.c
index 0de37d014524..33d30ee5bc84 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2302,7 +2302,7 @@ static int shmem_split_large_entry(struct inode *inode, pgoff_t index,
 	if (xas_error(&xas))
 		return xas_error(&xas);
 
-	return entry_order;
+	return 0;
 }
 
 /*
@@ -2323,7 +2323,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	struct swap_info_struct *si;
 	struct folio *folio = NULL;
 	bool skip_swapcache = false;
-	int error, nr_pages, order, split_order;
+	int error, nr_pages, order;
 	pgoff_t offset;
 
 	VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
@@ -2331,11 +2331,11 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	swap = index_entry;
 	*foliop = NULL;
 
-	if (is_poisoned_swp_entry(swap))
+	if (is_poisoned_swp_entry(index_entry))
 		return -EIO;
 
-	si = get_swap_device(swap);
-	order = shmem_confirm_swap(mapping, index, swap);
+	si = get_swap_device(index_entry);
+	order = shmem_confirm_swap(mapping, index, index_entry);
 	if (unlikely(!si)) {
 		if (order < 0)
 			return -EEXIST;
@@ -2347,6 +2347,12 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 		return -EEXIST;
 	}
 
+	/* index may point to the middle of a large entry, get the sub entry */
+	if (order) {
+		offset = index - round_down(index, 1 << order);
+		swap = swp_entry(swp_type(swap), swp_offset(swap) + offset);
+	}
+
 	/* Look it up and read it in.. */
 	folio = swap_cache_get_folio(swap, NULL, 0);
 	if (!folio) {
@@ -2359,7 +2365,8 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 
 		if (data_race(si->flags & SWP_SYNCHRONOUS_IO)) {
 			/* Direct swapin skipping swap cache & readahead */
-			folio = shmem_swap_alloc_folio(inode, vma, index, swap, order, gfp);
+			folio = shmem_swap_alloc_folio(inode, vma, index,
+						       index_entry, order, gfp);
 			if (IS_ERR(folio)) {
 				error = PTR_ERR(folio);
 				folio = NULL;
@@ -2367,16 +2374,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 			}
 			skip_swapcache = true;
 		} else {
-			/*
-			 * Cached swapin only supports order 0 folio, it is
-			 * necessary to recalculate the new swap entry based on
-			 * the offset, as the swapin index might be unalgined.
-			 */
-			if (order) {
-				offset = index - round_down(index, 1 << order);
-				swap = swp_entry(swp_type(swap), swp_offset(swap) + offset);
-			}
-
+			/* Cached swapin only supports order 0 folio */
 			folio = shmem_swapin_cluster(swap, gfp, info, index);
 			if (!folio) {
 				error = -ENOMEM;
@@ -2384,6 +2382,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 			}
 		}
 	}
+
 	if (order > folio_order(folio)) {
 		/*
 		 * Swapin may get smaller folios due to various reasons:
@@ -2393,24 +2392,25 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 		 * large swap entries. In such cases, we should split the
 		 * large swap entry to prevent possible data corruption.
 		 */
-		split_order = shmem_split_large_entry(inode, index, index_entry, gfp);
-		if (split_order < 0) {
-			error = split_order;
+		error = shmem_split_large_entry(inode, index, index_entry, gfp);
+		if (error)
 			goto failed_nolock;
-		}
+	}
 
-		/*
-		 * If the large swap entry has already been split, it is
-		 * necessary to recalculate the new swap entry based on
-		 * the old order alignment.
-		 */
-		if (split_order > 0) {
-			offset = index - round_down(index, 1 << split_order);
-			swap = swp_entry(swp_type(swap), swp_offset(index_entry) + offset);
-		}
-	} else if (order < folio_order(folio)) {
-		swap.val = round_down(swap.val, 1 << folio_order(folio));
-		index = round_down(index, 1 << folio_order(folio));
+	/*
+	 * If the folio is large, round down swap and index by folio size.
+	 * No matter what race occurs, the swap layer ensures we either get
+	 * a valid folio that has its swap entry aligned by size, or a
+	 * temporarily invalid one which we'll abort very soon and retry.
+	 *
+	 * shmem_add_to_page_cache ensures the whole range contains expected
+	 * entries and prevents any corruption, so any race split is fine
+	 * too, it will succeed as long as the entries are still there.
+	 */
+	nr_pages = folio_nr_pages(folio);
+	if (nr_pages > 1) {
+		swap.val = round_down(swap.val, nr_pages);
+		index = round_down(index, nr_pages);
 	}
 
 	/*
@@ -2446,8 +2446,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 			goto failed;
 	}
 
-	error = shmem_add_to_page_cache(folio, mapping,
-					round_down(index, nr_pages),
+	error = shmem_add_to_page_cache(folio, mapping, index,
 					swp_to_radix_entry(swap), gfp);
 	if (error)
 		goto failed;