Re: [PATCH] mm/vmscan: fix comment for current_may_throttle

[Andrew Morton]

On Thu, 14 Apr 2022 20:02:02 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:

> Since commit 6d6435811c19 ("remove bdi_congested() and wb_congested() and
> related functions"), there is no congested backing device check anymore.
> Correct the comment accordingly.
> 
> ...
>
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2334,8 +2334,7 @@ static unsigned int move_pages_to_lru(struct lruvec *lruvec,
>  /*
>   * If a kernel thread (such as nfsd for loop-back mounts) services
>   * a backing device by writing to the page cache it sets PF_LOCAL_THROTTLE.
> - * In that case we should only throttle if the backing device it is
> - * writing to is congested.  In other cases it is safe to throttle.
> + * In that case we should not throttle it otherwise it is safe to do so.
>   */
>  static int current_may_throttle(void)
>  {

That's a bit awkward to read.  I tweaked it, and reflowed the comment
to 80 cols.

--- a/mm/vmscan.c~mm-vmscan-fix-comment-for-current_may_throttle-fix
+++ a/mm/vmscan.c
@@ -2332,9 +2332,9 @@ static unsigned int move_pages_to_lru(st
 }
 
 /*
- * If a kernel thread (such as nfsd for loop-back mounts) services
- * a backing device by writing to the page cache it sets PF_LOCAL_THROTTLE.
- * In that case we should not throttle it otherwise it is safe to do so.
+ * If a kernel thread (such as nfsd for loop-back mounts) services a backing
+ * device by writing to the page cache it sets PF_LOCAL_THROTTLE. In this case
+ * we should not throttle.  Otherwise it is safe to do so.
  */
 static int current_may_throttle(void)
 {
_