[PATCHv5 17/17] mm/slab: Use compound_head() in page_slab()

From: Kiryl Shutsemau <kas@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
	Muchun Song <muchun.song@linux.dev>,
	David Hildenbrand <david@redhat.com>,
	Matthew Wilcox <willy@infradead.org>,
	Usama Arif <usamaarif642@gmail.com>,
	Frank van der Linden <fvdl@google.com>
Cc: Oscar Salvador <osalvador@suse.de>,
	Mike Rapoport <rppt@kernel.org>, Vlastimil Babka <vbabka@suse.cz>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
	Zi Yan <ziy@nvidia.com>, Baoquan He <bhe@redhat.com>,
	Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	kernel-team@meta.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	loongarch@lists.linux.dev, linux-riscv@lists.infradead.org,
	Kiryl Shutsemau <kas@kernel.org>
Subject: [PATCHv5 17/17] mm/slab: Use compound_head() in page_slab()
Date: Wed, 28 Jan 2026 13:54:58 +0000	[thread overview]
Message-ID: <20260128135500.22121-18-kas@kernel.org> (raw)
In-Reply-To: <20260128135500.22121-1-kas@kernel.org>

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@kernel.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

