From 652d12bc74a075f345f228f8945e05517a38874d Mon Sep 17 00:00:00 2001
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Date: Wed, 11 Feb 2026 12:31:38 +0200
Subject: mm: don't special case !MMU for is_zero_pfn() and my_zero_pfn()

Patch series "arch, mm: consolidate empty_zero_page", v3.

These patches cleanup handling of ZERO_PAGE() and zero_pfn.


This patch (of 4):

nommu architectures have empty_zero_page and define ZERO_PAGE() and
although they don't really use it to populate page tables, there is no
reason to hardwire !MMU implementation of is_zero_pfn() and my_zero_pfn()
to 0.

Drop #ifdef CONFIG_MMU around implementations of is_zero_pfn() and
my_zero_pfn() and remove !MMU version.

While on it, make zero_pfn __ro_after_init.

Link: https://lkml.kernel.org/r/20260211103141.3215197-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20260211103141.3215197-2-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/pgtable.h | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index a50df42a893f..5e772599d9a5 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1917,7 +1917,6 @@ static inline void pfnmap_setup_cachemode_pfn(unsigned long pfn, pgprot_t *prot)
 	pfnmap_setup_cachemode(pfn, PAGE_SIZE, prot);
 }
 
-#ifdef CONFIG_MMU
 #ifdef __HAVE_COLOR_ZERO_PAGE
 static inline int is_zero_pfn(unsigned long pfn)
 {
@@ -1940,18 +1939,7 @@ static inline unsigned long my_zero_pfn(unsigned long addr)
 	extern unsigned long zero_pfn;
 	return zero_pfn;
 }
-#endif
-#else
-static inline int is_zero_pfn(unsigned long pfn)
-{
-	return 0;
-}
-
-static inline unsigned long my_zero_pfn(unsigned long addr)
-{
-	return 0;
-}
-#endif /* CONFIG_MMU */
+#endif /* __HAVE_COLOR_ZERO_PAGE */
 
 #ifdef CONFIG_MMU
 
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