linux-kernel - Re: [PATCH 2/3] damon: Convert damon_pa_mark_accessed_or

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Date:   Wed,  7 Dec 2022 00:56:24 +0000
From:   SeongJae Park <sj@...nel.org>
To:     "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Cc:     linux-mm@...ck.org, damon@...ts.linux.dev,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        sj@...nel.org
Subject: Re: [PATCH 2/3] damon: Convert damon_pa_mark_accessed_or_deactivate() to use folios

Hi Vishal,

Thank you for this patch.

Nit pick.  Could we please replace 'damon:' on the subject with 'mm/damon:' to
look more consistent with other DAMON patches?

On Tue, 6 Dec 2022 16:21:57 -0800 "Vishal Moola (Oracle)" <vishal.moola@...il.com> wrote:

> This change replaces 2 calls to compound_head() with one.

I guess you mean _compound_head() calls in page_folio() that called from
mark_page_accessed() and folio_mark_accessed().  However, deactivate_page()
calls page_folio() anyway, so this patch doesn't reduce the number of calls to
one but keep the number, correct?  Am I missing something?  If I'm not, I'd
like to clean up the wording.

> This is in preparation for the conversion of deactivate_page() to
> deactivate_folio().

I think folio_deactivate() might be a more consistent naming.  What do you
think?

Also, you may keep the above sentence if you implement folio_deactivate()
first, update deactivate_page() calls to use folio_deactivate(), and finally
remove deactivate_page() definition.

I don't really care about the name and the sequence, though.

> 
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
> ---
>  mm/damon/paddr.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index e1a4315c4be6..73548bc82297 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -238,15 +238,18 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
>  
>  	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
>  		struct page *page = damon_get_page(PHYS_PFN(addr));
> +		struct folio *folio;
>  
>  		if (!page)
>  			continue;
> +		folio = page_folio(page);

One _compound_head() call here,

> +
>  		if (mark_accessed)
> -			mark_page_accessed(page);
> +			folio_mark_accessed(folio);
>  		else
> -			deactivate_page(page);
> -		put_page(page);
> -		applied++;
> +			deactivate_page(&folio->page);

And second _compound_head() call here.

> +		folio_put(folio);
> +		applied += folio_nr_pages(folio);
>  	}
>  	return applied * PAGE_SIZE;
>  }
> -- 
> 2.38.1
> 

Thanks,
SJ