linux-kernel - [PATCH v2 02/20] mm: factor out large folio handling from folio_nr_pages() into folio_large_nr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250224165603.1434404-3-david@redhat.com>
Date: Mon, 24 Feb 2025 17:55:44 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
	cgroups@...r.kernel.org,
	linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	linux-api@...r.kernel.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Tejun Heo <tj@...nel.org>,
	Zefan Li <lizefan.x@...edance.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Koutný <mkoutny@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Muchun Song <muchun.song@...ux.dev>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH v2 02/20] mm: factor out large folio handling from folio_nr_pages() into folio_large_nr_pages()

Let's factor it out into a simple helper function. This helper will
also come in handy when working with code where we know that our
folio is large.

While at it, let's consistently return a "long" value from all these
similar functions. Note that we cannot use "unsigned int" (even though
_folio_nr_pages is of that type), because it would break some callers
that do stuff like "-folio_nr_pages()". Both "int" or "unsigned long"
would work as well.

Maybe in the future we'll have the nr_pages readily available for all
large folios, maybe even for small folios, or maybe for none.

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 include/linux/mm.h | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index d00214e22a174..7c5a8fd29cfcd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1199,6 +1199,18 @@ static inline unsigned int folio_large_order(const struct folio *folio)
 	return folio->_flags_1 & 0xff;
 }
 
+#ifdef CONFIG_64BIT
+static inline long folio_large_nr_pages(const struct folio *folio)
+{
+	return folio->_folio_nr_pages;
+}
+#else
+static inline long folio_large_nr_pages(const struct folio *folio)
+{
+	return 1L << folio_large_order(folio);
+}
+#endif
+
 /*
  * compound_order() can be called without holding a reference, which means
  * that niceties like page_folio() don't work.  These callers should be
@@ -2141,11 +2153,7 @@ static inline long folio_nr_pages(const struct folio *folio)
 {
 	if (!folio_test_large(folio))
 		return 1;
-#ifdef CONFIG_64BIT
-	return folio->_folio_nr_pages;
-#else
-	return 1L << folio_large_order(folio);
-#endif
+	return folio_large_nr_pages(folio);
 }
 
 /* Only hugetlbfs can allocate folios larger than MAX_ORDER */
@@ -2160,24 +2168,20 @@ static inline long folio_nr_pages(const struct folio *folio)
  * page.  compound_nr() can be called on a tail page, and is defined to
  * return 1 in that case.
  */
-static inline unsigned long compound_nr(struct page *page)
+static inline long compound_nr(struct page *page)
 {
 	struct folio *folio = (struct folio *)page;
 
 	if (!test_bit(PG_head, &folio->flags))
 		return 1;
-#ifdef CONFIG_64BIT
-	return folio->_folio_nr_pages;
-#else
-	return 1L << folio_large_order(folio);
-#endif
+	return folio_large_nr_pages(folio);
 }
 
 /**
  * thp_nr_pages - The number of regular pages in this huge page.
  * @page: The head page of a huge page.
  */
-static inline int thp_nr_pages(struct page *page)
+static inline long thp_nr_pages(struct page *page)
 {
 	return folio_nr_pages((struct folio *)page);
 }
-- 
2.48.1