[patch 015/158] mm/gup.c: fix comments of __get_user_pages() and get_user_pages_remote()

[akpm@linux-foundation.org]

From: Liu Xiang <liuxiang_1999@126.com>
Subject: mm/gup.c: fix comments of __get_user_pages() and get_user_pages_remote()

Fix comments of __get_user_pages() and get_user_pages_remote(),
make them more clear.

Link: http://lkml.kernel.org/r/1572443533-3118-1-git-send-email-liuxiang_1999@126.com
Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |   32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

--- a/mm/gup.c~mm-gup-fix-comments-of-__get_user_pages-and-get_user_pages_remote
+++ a/mm/gup.c
@@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_are
  *		Or NULL if the caller does not require them.
  * @nonblocking: whether waiting for disk IO or mmap_sem contention
  *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno. Each page returned must be released
- * with a put_page() call when it is finished with. vmas will only
- * remain valid while mmap_sem is held.
+ * Returns either number of pages pinned (which may be less than the
+ * number requested), or an error. Details about the return value:
+ *
+ * -- If nr_pages is 0, returns 0.
+ * -- If nr_pages is >0, but no pages were pinned, returns -errno.
+ * -- If nr_pages is >0, and some pages were pinned, returns the number of
+ *    pages pinned. Again, this may be less than nr_pages.
+ *
+ * The caller is responsible for releasing returned @pages, via put_page().
+ *
+ * @vmas are valid only as long as mmap_sem is held.
  *
  * Must be called with mmap_sem held.  It may be released.  See below.
  *
@@ -1107,11 +1113,17 @@ static __always_inline long __get_user_p
  *		subsequently whether VM_FAULT_RETRY functionality can be
  *		utilised. Lock must initially be held.
  *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno. Each page returned must be released
- * with a put_page() call when it is finished with. vmas will only
- * remain valid while mmap_sem is held.
+ * Returns either number of pages pinned (which may be less than the
+ * number requested), or an error. Details about the return value:
+ *
+ * -- If nr_pages is 0, returns 0.
+ * -- If nr_pages is >0, but no pages were pinned, returns -errno.
+ * -- If nr_pages is >0, and some pages were pinned, returns the number of
+ *    pages pinned. Again, this may be less than nr_pages.
+ *
+ * The caller is responsible for releasing returned @pages, via put_page().
+ *
+ * @vmas are valid only as long as mmap_sem is held.
  *
  * Must be called with mmap_sem held for read or write.
  *
_