mm/debug_vm_pgtable: update comments regarding migration swap entries

Commit 4dd845b5 ("mm/swapops: rework swap entry manipulation code")
had changed migtation entry related helpers.  Just update
debug_vm_pgatble() synced documentation to reflect those changes.

Link: https://lkml.kernel.org/r/1641880417-24848-1-git-send-email-anshuman.khandual@arm.comSigned-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/arch_pgtable_helpers.rst

@@ -247,12 +247,12 @@ SWAP Page Table Helpers
 | __swp_to_pmd_entry        | Creates a mapped PMD from a swapped entry (arch) |
 +---------------------------+--------------------------------------------------+
 | is_migration_entry        | Tests a migration (read or write) swapped entry  |
-+---------------------------+--------------------------------------------------+
-| is_write_migration_entry  | Tests a write migration swapped entry            |
-+---------------------------+--------------------------------------------------+
-| make_migration_entry_read | Converts into read migration swapped entry       |
-+---------------------------+--------------------------------------------------+
-| make_migration_entry      | Creates a migration swapped entry (read or write)|
-+---------------------------+--------------------------------------------------+
++-------------------------------+----------------------------------------------+
+| is_writable_migration_entry   | Tests a write migration swapped entry        |
++-------------------------------+----------------------------------------------+
+| make_readable_migration_entry | Creates a read migration swapped entry       |
++-------------------------------+----------------------------------------------+
+| make_writable_migration_entry | Creates a write migration swapped entry      |
++-------------------------------+----------------------------------------------+
 
 [1] https://lore.kernel.org/linux-mm/20181017020930.GN30832@redhat.com/

mm/debug_vm_pgtable.c

@@ -888,8 +888,8 @@ static void __init swap_migration_tests(struct pgtable_debug_args *args)
 	pr_debug("Validating swap migration\n");
 
 	/*
-	 * make_migration_entry() expects given page to be
-	 * locked, otherwise it stumbles upon a BUG_ON().
+	 * make_[readable|writable]_migration_entry() expects given page to
+	 * be locked, otherwise it stumbles upon a BUG_ON().
 	 */
 	__SetPageLocked(page);
 	swp = make_writable_migration_entry(page_to_pfn(page));