linux-kernel - [PATCH RFC 3/6] mm: swap: make should_try_to_free

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Message-Id: <20240118111036.72641-4-21cnbao@gmail.com>
Date: Fri, 19 Jan 2024 00:10:33 +1300
From: Barry Song <21cnbao@...il.com>
To: ryan.roberts@....com,
	akpm@...ux-foundation.org,
	david@...hat.com,
	linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	mhocko@...e.com,
	shy828301@...il.com,
	wangkefeng.wang@...wei.com,
	willy@...radead.org,
	xiang@...nel.org,
	ying.huang@...el.com,
	yuzhao@...gle.com,
	surenb@...gle.com,
	steven.price@....com,
	Chuanhua Han <hanchuanhua@...o.com>,
	Barry Song <v-songbaohua@...o.com>
Subject: [PATCH RFC 3/6] mm: swap: make should_try_to_free_swap() support large-folio

From: Chuanhua Han <hanchuanhua@...o.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@...o.com>
Co-developed-by: Barry Song <v-songbaohua@...o.com>
Signed-off-by: Barry Song <v-songbaohua@...o.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