Re: [PATCH RFC 3/6] mm: swap: make should_try_to_free_swap() support large-folio

From: Chris Li <chrisl@kernel.org>
To: Barry Song <21cnbao@gmail.com>
Cc: ryan.roberts@arm.com, akpm@linux-foundation.org,
	david@redhat.com,  linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, mhocko@suse.com,
	 shy828301@gmail.com, wangkefeng.wang@huawei.com,
	willy@infradead.org,  xiang@kernel.org, ying.huang@intel.com,
	yuzhao@google.com, surenb@google.com,  steven.price@arm.com,
	Chuanhua Han <hanchuanhua@oppo.com>,
	 Barry Song <v-songbaohua@oppo.com>
Subject: Re: [PATCH RFC 3/6] mm: swap: make should_try_to_free_swap() support large-folio
Date: Fri, 26 Jan 2024 15:22:02 -0800	[thread overview]
Message-ID: <CAF8kJuPjXJVhh40k2utk80ho1y9j5OjvgGwxp1D_Qbt2AmL7KQ@mail.gmail.com> (raw)
In-Reply-To: <20240118111036.72641-4-21cnbao@gmail.com>

Acked-by: Chris Li <chrisl@kernel.org>

Chris

On Thu, Jan 18, 2024 at 3:11 AM Barry Song <21cnbao@gmail.com> wrote:
>
> From: Chuanhua Han <hanchuanhua@oppo.com>
>
> should_try_to_free_swap() works with an assumption that swap-in is always done
> at normal page granularity, aka, folio_nr_pages = 1. To support large folio
> swap-in, this patch removes the 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>
> ---
>  mm/memory.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 7e1f4849463a..f61a48929ba7 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3714,7 +3714,7 @@ 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)
> --
> 2.34.1
>
>