linux-kernel - Re: [PATCH 2/7] mm, swap: drop the flag TTRS

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Message-ID: <Z7VFELM19eiDUzOJ@MiWiFi-R3L-srv>
Date: Wed, 19 Feb 2025 10:42:24 +0800
From: Baoquan He <bhe@...hat.com>
To: Kairui Song <kasong@...cent.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Chris Li <chrisl@...nel.org>, Barry Song <v-songbaohua@...o.com>,
	Hugh Dickins <hughd@...gle.com>,
	Yosry Ahmed <yosryahmed@...gle.com>,
	"Huang, Ying" <ying.huang@...ux.alibaba.com>,
	Nhat Pham <nphamcs@...il.com>, Johannes Weiner <hannes@...xchg.org>,
	Kalesh Singh <kaleshsingh@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/7] mm, swap: drop the flag TTRS_DIRECT

On 02/15/25 at 01:57am, Kairui Song wrote:
> From: Kairui Song <kasong@...cent.com>
> 
> This flag exists temporarily to allow the allocator to bypass the slot
> cache during freeing, so reclaiming one slot will free the slot
> immediately.
> 
> But now we have already removed slot cache usage on freeing, so this
> flag has no effect now.
> 
> Signed-off-by: Kairui Song <kasong@...cent.com>
> ---
>  mm/swapfile.c | 23 +++--------------------
>  1 file changed, 3 insertions(+), 20 deletions(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index c77ffee4af86..449e388a6fec 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c

Reviewed-by: Baoquan He <bhe@...haat.com>

> @@ -158,8 +158,6 @@ static long swap_usage_in_pages(struct swap_info_struct *si)
>  #define TTRS_UNMAPPED		0x2
>  /* Reclaim the swap entry if swap is getting full */
>  #define TTRS_FULL		0x4
> -/* Reclaim directly, bypass the slot cache and don't touch device lock */
> -#define TTRS_DIRECT		0x8
>  
>  static bool swap_only_has_cache(struct swap_info_struct *si,
>  			      unsigned long offset, int nr_pages)
> @@ -257,23 +255,8 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si,
>  	if (!need_reclaim)
>  		goto out_unlock;
>  
> -	if (!(flags & TTRS_DIRECT)) {
> -		/* Free through slot cache */
> -		delete_from_swap_cache(folio);
> -		folio_set_dirty(folio);
> -		ret = nr_pages;
> -		goto out_unlock;
> -	}
> -
> -	xa_lock_irq(&address_space->i_pages);
> -	__delete_from_swap_cache(folio, entry, NULL);
> -	xa_unlock_irq(&address_space->i_pages);
> -	folio_ref_sub(folio, nr_pages);
> +	delete_from_swap_cache(folio);
>  	folio_set_dirty(folio);
> -
> -	ci = lock_cluster(si, offset);
> -	swap_entry_range_free(si, ci, entry, nr_pages);
> -	unlock_cluster(ci);
>  	ret = nr_pages;
>  out_unlock:
>  	folio_unlock(folio);
> @@ -707,7 +690,7 @@ static bool cluster_reclaim_range(struct swap_info_struct *si,
>  			offset++;
>  			break;
>  		case SWAP_HAS_CACHE:
> -			nr_reclaim = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY | TTRS_DIRECT);
> +			nr_reclaim = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY);
>  			if (nr_reclaim > 0)
>  				offset += nr_reclaim;
>  			else
> @@ -860,7 +843,7 @@ static void swap_reclaim_full_clusters(struct swap_info_struct *si, bool force)
>  			if (READ_ONCE(map[offset]) == SWAP_HAS_CACHE) {
>  				spin_unlock(&ci->lock);
>  				nr_reclaim = __try_to_reclaim_swap(si, offset,
> -								   TTRS_ANYWAY | TTRS_DIRECT);
> +								   TTRS_ANYWAY);
>  				spin_lock(&ci->lock);
>  				if (nr_reclaim) {
>  					offset += abs(nr_reclaim);
> -- 
> 2.48.1
>