Re: [PATCH v2 2/3] mm/damon/paddr: minor refactor of damon_pa_young()

SeongJae Park
2023-03-03T18:39:31Z

Hi Kefeng,

On Fri, 3 Mar 2023 16:43:42 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> Omit three lines by unified folio_put(), and make code more clear.
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> mm/damon/paddr.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index 3fda00a0f786..2ef9db0189ca 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -130,24 +130,21 @@ static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
> accessed = false;
> else
> accessed = true;
> - folio_put(folio);
> goto out;

Because you moved 'out' label to not include *folio_sz setting, folio_sz will
not set in this case. It should be set.

> }
>
> need_lock = !folio_test_anon(folio) || folio_test_ksm(folio);
> - if (need_lock && !folio_trylock(folio)) {
> - folio_put(folio);
> - return false;
> - }
> + if (need_lock && !folio_trylock(folio))
> + goto out;
>
> rmap_walk(folio, &rwc);
>
> if (need_lock)
> folio_unlock(folio);
> - folio_put(folio);
>
> -out:
> *folio_sz = folio_size(folio);
> +out:
> + folio_put(folio);

Before this change, folio_size() is called after folio_put(). Shouldn't it be
called before folio_put()? If so, could we make a separate fix for that first,
and then make this change on top of it, so that it can be easily applied to
relevant stable kernels?

Thanks,
SJ

> return accessed;
> }
>
> --
> 2.35.3
>
>