Re: [PATCH RFC] mm/swap: make release_pages() and put_pages() match

[Shakeel Butt]

On Fri, May 24, 2019 at 12:33 PM <ira.weiny@xxxxxxxxx> wrote:
>
> From: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> RFC I have no idea if this is correct or not.  But looking at
> release_pages() I see a call to both __ClearPageActive() and
> __ClearPageWaiters() while in __page_cache_release() I do not.
>
> Is this a bug which needs to be fixed?  Did I miss clearing active
> somewhere else in the call chain of put_page?
>
> This was found via code inspection while determining if release_pages()
> and the new put_user_pages() could be interchangeable.
>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
>  mm/swap.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index 3a75722e68a9..9d0432baddb0 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -69,6 +69,7 @@ static void __page_cache_release(struct page *page)
>                 del_page_from_lru_list(page, lruvec, page_off_lru(page));

see page_off_lru(page) above which clear active bit.

>                 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
>         }
> +       __ClearPageActive(page);
>         __ClearPageWaiters(page);
>         mem_cgroup_uncharge(page);
>  }
> --
> 2.20.1
>