linux-kernel - [PATCH v2 2/2] mm/huge_memory: use folio_expected_ref_count() to calculate ref

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Message-ID: <20250711182355.3592618-3-ziy@nvidia.com>
Date: Fri, 11 Jul 2025 14:23:55 -0400
From: Zi Yan <ziy@...dia.com>
To: Balbir Singh <balbirs@...dia.com>,
	David Hildenbrand <david@...hat.com>,
	linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Kirill Shutemov <k.shutemov@...il.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Zi Yan <ziy@...dia.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Nico Pache <npache@...hat.com>,
	Ryan Roberts <ryan.roberts@....com>,
	Dev Jain <dev.jain@....com>,
	Barry Song <baohua@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] mm/huge_memory: use folio_expected_ref_count() to calculate ref_count.

Instead of open coding the ref_count calculation, use
folio_expected_ref_count().

Suggested-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Zi Yan <ziy@...dia.com>
---
 mm/huge_memory.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 818a6bd9f0d4..57e5699cf638 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3739,6 +3739,7 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 	if (folio_ref_freeze(folio, 1 + extra_pins)) {
 		struct address_space *swap_cache = NULL;
 		struct lruvec *lruvec;
+		int expected_refs;
 
 		if (folio_order(folio) > 1 &&
 		    !list_empty(&folio->_deferred_list)) {
@@ -3809,11 +3810,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 		     new_folio = next) {
 			next = folio_next(new_folio);
 
-			folio_ref_unfreeze(
-				new_folio,
-				1 + ((mapping || swap_cache) ?
-					     folio_nr_pages(new_folio) :
-					     0));
+			expected_refs = folio_expected_ref_count(new_folio) + 1;
+			folio_ref_unfreeze(new_folio, expected_refs);
 
 			lru_add_split_folio(folio, new_folio, lruvec, list);
 
@@ -3843,8 +3841,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 		 * Otherwise, a parallel folio_try_get() can grab origin_folio
 		 * and its caller can see stale page cache entries.
 		 */
-		folio_ref_unfreeze(folio, 1 +
-			((mapping || swap_cache) ? folio_nr_pages(folio) : 0));
+		expected_refs = folio_expected_ref_count(folio) + 1;
+		folio_ref_unfreeze(folio, expected_refs);
 
 		unlock_page_lruvec(lruvec);
 
-- 
2.47.2