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

Kefeng Wang
2023-03-06T01:10:45Z

On 2023/3/4 2:39, SeongJae Park wrote:
> 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.
oh, it should be fixed.
>
>> }
>>
>> 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?
>
Yes， I could separate it, after folio_put(), the folio could be
re-allocated and the folio_size calculation is not right.
>
> Thanks,
> SJ
>
>> return accessed;
>> }
>>
>> --
>> 2.35.3
>>
>>