diff --git a/mm/shmem.c b/mm/shmem.c
index 21ef93c92b47..dd4eb11c84b5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1664,6 +1664,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
 	unsigned long mask = READ_ONCE(huge_shmem_orders_always);
 	unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
 	unsigned long vm_flags = vma ? vma->vm_flags : 0;
+	pgoff_t aligned_index;
 	bool global_huge;
 	loff_t i_size;
 	int order;
@@ -1698,9 +1699,9 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
 	/* Allow mTHP that will be fully within i_size. */
 	order = highest_order(within_size_orders);
 	while (within_size_orders) {
-		index = round_up(index + 1, order);
+		aligned_index = round_up(index + 1, 1 << order);
 		i_size = round_up(i_size_read(inode), PAGE_SIZE);
-		if (i_size >> PAGE_SHIFT >= index) {
+		if (i_size >> PAGE_SHIFT >= aligned_index) {
 			mask |= within_size_orders;
 			break;
 		}