From nobody Tue Feb 10 20:47:06 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D08CC37BE65; Mon, 9 Feb 2026 14:41:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770648086; cv=none; b=l6ZLELjsbR7Queb3GbJ2gFHu8YelM6NoLy+ADrsW8lrkd2LuIRNZUmyoyjLifZhhk6Sti6T7JwzDfjslcMSGG0GPidqTRKFLN9xX8Kd0zS+SKba7ksY0LNZaITaMBchSZD1gUvXALFr1AVwazdaKE607IDwrrfYRvF/IRQDGuYU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770648086; c=relaxed/simple; bh=IrP0HcvbxJyr+QPUUgTWRvTOZExBIyn/P520HSFeTE0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s1jwqFradrzw3UjDM237W1mjTxQQ5f9TiiMiQoc1HoFPI9zikyFeMeAv7XmGwFh+g1WQXM/n1C3fIMfEWE04pG0J3gFWuywzjNxK6Wk5KHuy1xjpwwrDJEozwqFaNpwocExZSjgT08d1K5Rh1Ddg7/PLtNmZiSH9y3PMhEKIwQQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=APyMK8Xc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="APyMK8Xc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4BD7C16AAE; Mon, 9 Feb 2026 14:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770648086; bh=IrP0HcvbxJyr+QPUUgTWRvTOZExBIyn/P520HSFeTE0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=APyMK8Xcr0Pj/4H/7ScdM60IKK2Af+gkFXGdQhPjdHsnmzLsJm02Nchy+jJL23anM bNBnoHk9xK2QiZTV+rQY/KLwerxB3VnzQfxzTkQc1iH70KMN3Z0GuLpljati7S0tf8 ls86zRd33YVz+J6pURgPRqvGX5Q/n+dPhzCqdL5yV63J60pinW1+OsSd3d1xFDgsvS 6up5zQsE5HXsLq3bdag17WhUQCgbBwXYJxsH7xLXV9rnrG9HIsZoWR0mYcQZNF9Lk2 3fCjxQBhoGvtiYzXnS5lcX8tXcaTibT8zTyCBbpHKv+p0HdsmTNf1IjvNxObtwAPb6 sxyY+fXDu7Mnw== From: Mike Rapoport To: Andrew Morton Cc: Andreas Larsson , Borislav Petkov , Brian Cain , Catalin Marinas , "Christophe Leroy (CS GROUP)" , "David S. Miller" , Dave Hansen , David Hildenbrand , Dinh Nguyen , Geert Uytterhoeven , Guo Ren , Helge Deller , Huacai Chen , Ingo Molnar , Johannes Berg , John Paul Adrian Glaubitz , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Magnus Lindholm , Matt Turner , Max Filippov , Michael Ellerman , Michal Hocko , Michal Simek , Mike Rapoport , Palmer Dabbelt , Richard Weinberger , Russell King , Stafford Horne , Suren Baghdasaryan , Thomas Gleixner , Vineet Gupta , Vlastimil Babka , Will Deacon , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org Subject: [PATCH v2 1/4] mm: don't special case !MMU for is_zero_pfn() and my_zero_pfn() Date: Mon, 9 Feb 2026 16:40:54 +0200 Message-ID: <20260209144058.2092871-2-rppt@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260209144058.2092871-1-rppt@kernel.org> References: <20260209144058.2092871-1-rppt@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Mike Rapoport (Microsoft)" 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. Signed-off-by: Mike Rapoport (Microsoft) --- include/linux/pgtable.h | 14 +------------- mm/memory.c | 13 ------------- mm/mm_init.c | 10 ++++++++++ 3 files changed, 11 insertions(+), 26 deletions(-) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 827dca25c0bc..08a88b0d56e5 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1882,7 +1882,6 @@ static inline void pfnmap_setup_cachemode_pfn(unsigne= d long pfn, pgprot_t *prot) pfnmap_setup_cachemode(pfn, PAGE_SIZE, prot); } =20 -#ifdef CONFIG_MMU #ifdef __HAVE_COLOR_ZERO_PAGE static inline int is_zero_pfn(unsigned long pfn) { @@ -1905,18 +1904,7 @@ static inline unsigned long my_zero_pfn(unsigned lon= g 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 */ =20 #ifdef CONFIG_MMU =20 diff --git a/mm/memory.c b/mm/memory.c index 187f16b7e996..51d2018a387a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -162,21 +162,8 @@ static int __init disable_randmaps(char *s) } __setup("norandmaps", disable_randmaps); =20 -unsigned long zero_pfn __read_mostly; -EXPORT_SYMBOL(zero_pfn); - unsigned long highest_memmap_pfn __read_mostly; =20 -/* - * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() - */ -static int __init init_zero_pfn(void) -{ - zero_pfn =3D page_to_pfn(ZERO_PAGE(0)); - return 0; -} -early_initcall(init_zero_pfn); - void mm_trace_rss_stat(struct mm_struct *mm, int member) { trace_rss_stat(mm, member); diff --git a/mm/mm_init.c b/mm/mm_init.c index 1a29a719af58..dcf9eff34f83 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -53,6 +53,9 @@ EXPORT_SYMBOL(mem_map); void *high_memory; EXPORT_SYMBOL(high_memory); =20 +unsigned long zero_pfn __ro_after_init; +EXPORT_SYMBOL(zero_pfn); + #ifdef CONFIG_DEBUG_MEMORY_INIT int __meminitdata mminit_loglevel; =20 @@ -2667,6 +2670,13 @@ static void __init mem_init_print_info(void) ); } =20 +static int __init init_zero_pfn(void) +{ + zero_pfn =3D page_to_pfn(ZERO_PAGE(0)); + return 0; +} +early_initcall(init_zero_pfn); + void __init __weak arch_mm_preinit(void) { } --=20 2.51.0