linux-kernel - [PATCHv5 17/17] mm/slab: Use compound_head() in page

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Message-ID: <20260128135500.22121-18-kas@kernel.org>
Date: Wed, 28 Jan 2026 13:54:58 +0000
From: Kiryl Shutsemau <kas@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>,
	David Hildenbrand <david@...hat.com>,
	Matthew Wilcox <willy@...radead.org>,
	Usama Arif <usamaarif642@...il.com>,
	Frank van der Linden <fvdl@...gle.com>
Cc: Oscar Salvador <osalvador@...e.de>,
	Mike Rapoport <rppt@...nel.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Zi Yan <ziy@...dia.com>,
	Baoquan He <bhe@...hat.com>,
	Michal Hocko <mhocko@...e.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Jonathan Corbet <corbet@....net>,
	Huacai Chen <chenhuacai@...nel.org>,
	WANG Xuerui <kernel@...0n.name>,
	Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	kernel-team@...a.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-riscv@...ts.infradead.org,
	Kiryl Shutsemau <kas@...nel.org>
Subject: [PATCHv5 17/17] mm/slab: Use compound_head() in page_slab()

page_slab() contained an open-coded implementation of compound_head().

Replace the duplicated code with a direct call to compound_head().

Signed-off-by: Kiryl Shutsemau <kas@...nel.org>

---

I am not sure if this open-coded version is intentional and required for
memdesc transition. Drop the patch if it is.
---
 mm/slab.h | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/mm/slab.h b/mm/slab.h
index f68c3ac8126f..970a13ac5b8e 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -137,19 +137,7 @@ static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(struct freelist
  */
 static inline struct slab *page_slab(const struct page *page)
 {
-	unsigned long info;
-
-	info = READ_ONCE(page->compound_info);
-	if (info & 1) {
-		/* See compound_head() */
-		if (compound_info_has_mask()) {
-			unsigned long p = (unsigned long)page;
-			page = (struct page *)(p & info);
-		} else {
-			page = (struct page *)(info - 1);
-		}
-	}
-
+	page = compound_head(page);
 	if (data_race(page->page_type >> 24) != PGTY_slab)
 		page = NULL;
 
-- 
2.51.2