Re: [PATCH] mm/z3fold.c: fix lock/unlock imbalance in z3fold_page_isolate

[Andrew Morton]

On Sun, 25 Aug 2019 22:06:34 -0500 "Gustavo A. R. Silva" 
<gust...@embeddedor.com> wrote:

> Fix lock/unlock imbalance by unlocking *zhdr* before return.
> 
> Addresses-Coverity-ID: 1452811 ("Missing unlock")
> Fixes: d776aaa9895e ("mm/z3fold.c: fix race between migration and 
> destruction")
> Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
> ---
>  mm/z3fold.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index e31cd9bd4ed5..75b7962439ff 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -1406,6 +1406,7 @@ static bool z3fold_page_isolate(struct page *page, 
> isolate_mode_t mode)
>                                * should freak out.
>                                */
>                               WARN(1, "Z3fold is experiencing kref 
> problems\n");
> +                             z3fold_page_unlock(zhdr);
>                               return false;
>                       }
>                       z3fold_page_unlock(zhdr);

Looks good, thanks.


This is a bit silly:

                        if (..) {
                                ...
                                z3fold_page_unlock(zhdr);
                                return false;
                        }
                        z3fold_page_unlock(zhdr);
                        return false;

but presumably the compiler will clean up after us.