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Date: Mon, 6 May 2024 10:14:58 +0200
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Subject: Re: [PATCH v3 5/6] mm: swap: make should_try_to_free_swap() support
 large-folio
To: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org,
 linux-mm@kvack.org
Cc: baolin.wang@linux.alibaba.com, chrisl@kernel.org, hanchuanhua@oppo.com,
 hannes@cmpxchg.org, hughd@google.com, kasong@tencent.com,
 linux-kernel@vger.kernel.org, ryan.roberts@arm.com, surenb@google.com,
 v-songbaohua@oppo.com, willy@infradead.org, xiang@kernel.org,
 ying.huang@intel.com, yosryahmed@google.com, yuzhao@google.com,
 ziy@nvidia.com
References: <20240503005023.174597-1-21cnbao@gmail.com>
 <20240503005023.174597-6-21cnbao@gmail.com>
From: David Hildenbrand <david@redhat.com>
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In-Reply-To: <20240503005023.174597-6-21cnbao@gmail.com>
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On 03.05.24 02:50, Barry Song wrote:
> From: Chuanhua Han <hanchuanhua@oppo.com>
> 
> The function should_try_to_free_swap() operates under the assumption
> that swap-in always occurs at the normal page granularity,
> i.e., folio_nr_pages() = 1. However, in reality, for large folios,
> add_to_swap_cache() will invoke folio_ref_add(folio, nr).  To accommodate
> large folio swap-in, this patch eliminates this assumption.
> 
> Signed-off-by: Chuanhua Han <hanchuanhua@oppo.com>
> Co-developed-by: Barry Song <v-songbaohua@oppo.com>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> Acked-by: Chris Li <chrisl@kernel.org>
> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
> Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
> ---
>   mm/memory.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 74cdefd58f5f..22e7c33cc747 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3877,7 +3877,7 @@ static inline bool should_try_to_free_swap(struct folio *folio,
>   	 * reference only in case it's likely that we'll be the exlusive user.
>   	 */
>   	return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
> -		folio_ref_count(folio) == 2;
> +		folio_ref_count(folio) == (1 + folio_nr_pages(folio));
>   }
>   
>   static vm_fault_t pte_marker_clear(struct vm_fault *vmf)


Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb