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

[Kefeng Wang]

On 2023/3/4 2:39, SeongJae Park wrote:
> Hi Kefeng,
>
> On Fri, 3 Mar 2023 16:43:42 +0800 Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
>
> > Omit three lines by unified folio_put(), and make code more clear.
> >
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   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