linux-kernel - Re: [PATCH 8/9] mm: swap: factor out helper to drop cache of entries within a single cluster

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Message-ID: <b2d809dfff16cebc7d83ca2884b0fa6fe1024797.camel@linux.intel.com>
Date: Fri, 14 Mar 2025 17:24:47 -0700
From: Tim Chen <tim.c.chen@...ux.intel.com>
To: Kemeng Shi <shikemeng@...weicloud.com>, akpm@...ux-foundation.org
Cc: kasong@...cent.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/9] mm: swap: factor out helper to drop cache of
 entries within a single cluster

On Fri, 2025-03-14 at 05:05 +0800, Kemeng Shi wrote:
> Factor out helper swap_entries_put_cache() from put_swap_folio() to server
> as a general-purpose routine for dropping cache flag of entries within a
> single cluster.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Reviewed-by: Tim Chen <tim.c.chen@...ux.intel.com>

> ---
>  mm/swapfile.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index ebac9ff74ba7..343b34eb2a81 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1473,6 +1473,21 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry)
>  	return NULL;
>  }
>  
> +static void swap_entries_put_cache(struct swap_info_struct *si,
> +				   swp_entry_t entry, int nr)
> +{
> +	unsigned long offset = swp_offset(entry);
> +	struct swap_cluster_info *ci;
> +
> +	ci = lock_cluster(si, offset);
> +	if (swap_only_has_cache(si, offset, nr))
> +		swap_entries_free(si, ci, entry, nr);
> +	else
> +		for (int i = 0; i < nr; i++, entry.val++)
> +			swap_entry_put_locked(si, ci, entry, SWAP_HAS_CACHE);
> +	unlock_cluster(ci);
> +}
> +
>  static bool swap_entries_put_map(struct swap_info_struct *si,
>  				 swp_entry_t entry, int nr)
>  {
> @@ -1597,8 +1612,6 @@ void swap_free_nr(swp_entry_t entry, int nr_pages)
>   */
>  void put_swap_folio(struct folio *folio, swp_entry_t entry)
>  {
> -	unsigned long offset = swp_offset(entry);
> -	struct swap_cluster_info *ci;
>  	struct swap_info_struct *si;
>  	int size = 1 << swap_entry_order(folio_order(folio));
>  
> @@ -1606,13 +1619,7 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry)
>  	if (!si)
>  		return;
>  
> -	ci = lock_cluster(si, offset);
> -	if (swap_only_has_cache(si, offset, size))
> -		swap_entries_free(si, ci, entry, size);
> -	else
> -		for (int i = 0; i < size; i++, entry.val++)
> -			swap_entry_put_locked(si, ci, entry, SWAP_HAS_CACHE);
> -	unlock_cluster(ci);
> +	swap_entries_put_cache(si, entry, size);
>  }
>  
>  int __swap_count(swp_entry_t entry)