diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 7572925..2cc78a5 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -90,6 +90,8 @@ static struct kmem_cache *mm_slot_cache __read_mostly;
  * @hash: hash collision list
  * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
  * @mm: the mm that this information is valid for
+ * @nr_pte_mapped_thp: number of pte mapped THP
+ * @pte_mapped_thp: address array corresponding pte mapped THP
  */
 struct mm_slot {
 	struct hlist_node hash;
@@ -1414,7 +1416,11 @@ static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
 }
 
 /**
- * Try to collapse a pte-mapped THP for mm at address haddr.
+ * collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at
+ * address haddr.
+ *
+ * @mm: process address space where collapse happens
+ * @addr: THP collapse address
  *
  * This function checks whether all the PTEs in the PMD are pointing to the
  * right THP. If so, retract the page table so the THP can refault in with
@@ -1605,6 +1611,12 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
 /**
  * collapse_file - collapse filemap/tmpfs/shmem pages into huge one.
  *
+ * @mm: process address space where collapse happens
+ * @file: file that collapse on
+ * @start: collapse start address
+ * @hpage: new allocated huge page for collapse
+ * @node: appointed node the new huge page allocate from
+ *
  * Basic scheme is simple, details are more complex:
  *  - allocate and lock a new huge page;
  *  - scan page cache replacing old pages with the new one