mm: update mmap_sem comments to refer to mmap_lock

The rename from mm->mmap_sem to mm->mmap_lock was performed in commit
da1c55f ("mmap locking API: rename mmap_sem to mmap_lock") and commit
c1e8d7c ("map locking API: convert mmap_sem comments"), however some
incorrect comments remain.

This patch simply corrects those comments which are obviously incorrect
within mm itself.

Link: https://lkml.kernel.org/r/33fba04389ab63fc4980e7ba5442f521df6dc657.1673048927.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm_types.h

@@ -581,7 +581,7 @@ struct vm_area_struct {
 	/*
 	 * For private and shared anonymous mappings, a pointer to a null
 	 * terminated string containing the name given to the vma, or NULL if
-	 * unnamed. Serialized by mmap_sem. Use anon_vma_name to access.
+	 * unnamed. Serialized by mmap_lock. Use anon_vma_name to access.
 	 */
 	struct anon_vma_name *anon_name;
 #endif

include/linux/page_ref.h

@@ -301,7 +301,7 @@ static inline bool folio_ref_try_add_rcu(struct folio *folio, int count)
  *
  * You can also use this function if you're holding a lock that prevents
  * pages being frozen & removed; eg the i_pages lock for the page cache
- * or the mmap_sem or page table lock for page tables.  In this case,
+ * or the mmap_lock or page table lock for page tables.  In this case,
  * it will always succeed, and you could have used a plain folio_get(),
  * but it's sometimes more convenient to have a common function called
  * from both locked and RCU-protected contexts.

mm/hugetlb.c

@@ -1183,7 +1183,7 @@ void hugetlb_dup_vma_private(struct vm_area_struct *vma)
 
 /*
  * Reset and decrement one ref on hugepage private reservation.
- * Called with mm->mmap_sem writer semaphore held.
+ * Called with mm->mmap_lock writer semaphore held.
  * This function should be only used by move_vma() and operate on
  * same sized vma. It should never come here with last ref on the
  * reservation.
@@ -5152,7 +5152,7 @@ static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr,
 
 	/*
 	 * We don't have to worry about the ordering of src and dst ptlocks
-	 * because exclusive mmap_sem (or the i_mmap_lock) prevents deadlock.
+	 * because exclusive mmap_lock (or the i_mmap_lock) prevents deadlock.
 	 */
 	if (src_ptl != dst_ptl)
 		spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);

mm/madvise.c

@@ -130,7 +130,7 @@ static int replace_anon_vma_name(struct vm_area_struct *vma,
 #endif /* CONFIG_ANON_VMA_NAME */
 /*
  * Update the vm_flags on region of a vma, splitting it or merging it as
- * necessary.  Must be called with mmap_sem held for writing;
+ * necessary.  Must be called with mmap_lock held for writing;
  * Caller should ensure anon_name stability by raising its refcount even when
  * anon_name belongs to a valid vma because this function might free that vma.
  */

mm/mmap.c

@@ -2294,7 +2294,7 @@ static inline int munmap_sidetree(struct vm_area_struct *vma,
  * @start: The aligned start address to munmap.
  * @end: The aligned end address to munmap.
  * @uf: The userfaultfd list_head
- * @downgrade: Set to true to attempt a write downgrade of the mmap_sem
+ * @downgrade: Set to true to attempt a write downgrade of the mmap_lock
  *
  * If @downgrade is true, check return code for potential release of the lock.
  */
@@ -2469,7 +2469,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
  * @len: The length of the range to munmap
  * @uf: The userfaultfd list_head
  * @downgrade: set to true if the user wants to attempt to write_downgrade the
- * mmap_sem
+ * mmap_lock
  *
  * This function takes a @mas that is either pointing to the previous VMA or set
  * to MA_START and sets it up to remove the mapping(s).  The @len will be