mm: fix kernel-doc markups

Kernel-doc markups should use this format:
        identifier - description

Fix some issues on mm files:

1) The definition for get_user_pages_locked() doesn't follow it.  Also,
   it expects a short descrpition at the header, followed by a long one,
   after the parameters.  Fix it.

2) Kernel-doc requires that a kernel-doc markup to be immediately below
   the function prototype, as otherwise it will rename it.  So, move
   get_pfnblock_flags_mask() description to the right place.

3) Make invalidate_mapping_pagevec() to also follow the expected
   kernel-doc format.

While here, fix a few minor English syntax issues, as suggested
by Matthew:
	will used -> will be used
	similar with -> similar to

Link: https://lkml.kernel.org/r/80e85dddc92d333bc2159ee8a2294921612e8745.1605521731.git.mchehab+huawei@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Suggested-by: Mattew Wilcox <willy@infradead.org>	[English fixes]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/gup.c

@@ -1845,7 +1845,19 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 EXPORT_SYMBOL(get_user_pages);
 
 /**
- * get_user_pages_locked() is suitable to replace the form:
+ * get_user_pages_locked() - variant of get_user_pages()
+ *
+ * @start:      starting user address
+ * @nr_pages:   number of pages from start to pin
+ * @gup_flags:  flags modifying lookup behaviour
+ * @pages:      array that receives pointers to the pages pinned.
+ *              Should be at least nr_pages long. Or NULL, if caller
+ *              only intends to ensure the pages are faulted in.
+ * @locked:     pointer to lock flag indicating whether lock is held and
+ *              subsequently whether VM_FAULT_RETRY functionality can be
+ *              utilised. Lock must initially be held.
+ *
+ * It is suitable to replace the form:
  *
  *      mmap_read_lock(mm);
  *      do_something()
@@ -1861,16 +1873,6 @@ EXPORT_SYMBOL(get_user_pages);
  *      if (locked)
  *          mmap_read_unlock(mm);
  *
- * @start:      starting user address
- * @nr_pages:   number of pages from start to pin
- * @gup_flags:  flags modifying lookup behaviour
- * @pages:      array that receives pointers to the pages pinned.
- *              Should be at least nr_pages long. Or NULL, if caller
- *              only intends to ensure the pages are faulted in.
- * @locked:     pointer to lock flag indicating whether lock is held and
- *              subsequently whether VM_FAULT_RETRY functionality can be
- *              utilised. Lock must initially be held.
- *
  * We can leverage the VM_FAULT_RETRY functionality in the page fault
  * paths better by using either get_user_pages_locked() or
  * get_user_pages_unlocked().

mm/page_alloc.c

@@ -470,14 +470,6 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
 	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 }
 
-/**
- * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
- * @page: The page within the block of interest
- * @pfn: The target page frame number
- * @mask: mask of bits that the caller is interested in
- *
- * Return: pageblock_bits flags
- */
 static __always_inline
 unsigned long __get_pfnblock_flags_mask(struct page *page,
 					unsigned long pfn,
@@ -496,6 +488,14 @@ unsigned long __get_pfnblock_flags_mask(struct page *page,
 	return (word >> bitidx) & mask;
 }
 
+/**
+ * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @pfn: The target page frame number
+ * @mask: mask of bits that the caller is interested in
+ *
+ * Return: pageblock_bits flags
+ */
 unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
 					unsigned long mask)
 {

mm/truncate.c

@@ -643,9 +643,9 @@ EXPORT_SYMBOL(invalidate_mapping_pages);
  * @end: the offset 'to' which to invalidate (inclusive)
  * @nr_pagevec: invalidate failed page number for caller
  *
- * This helper is similar with invalidate_mapping_pages, except that it accounts
+ * This helper is similar to invalidate_mapping_pages(), except that it accounts
- * for pages that failed to invalidate on a pagevec and count them in
+ * for pages that are likely on a pagevec and counts them in @nr_pagevec, which
- * @nr_pagevec, which will used by the caller.
+ * will be used by the caller.
  */
 void invalidate_mapping_pagevec(struct address_space *mapping,
 		pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)