From mboxrd@z Thu Jan 1 00:00:00 1970 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 30F6C366054; Mon, 23 Feb 2026 12:37:50 +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=1771850270; cv=none; b=d+PDaFZpQQJDZOpsHjhUsoJ9jj8nZwr6bYTKb7+JE27oAGWwRYSfCz12/3Xf0nu43nW5X8PrkFvopRcnhxKplpwlfQ1ztSXHnEcm4oPQSMNCcWdXOyxAr5YG12/zExgkQJlzOYgMbCgxK4I+PGDm6jQcBWL7L8dQ2JhCDnTecYA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771850270; c=relaxed/simple; bh=DARLU9PRhXEqGMQEgxyxiRXMnp76keYf4PJl96EYaKs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Oap5rTy7ePMXEyq4m8QwAq0P9FYpUf80b3yhFF9OToiNlessQ/AOqUucQA1lp3sY326J7eJ+zbyxBJrfjJP6X+gxJQs5USvRbkdB8Y9GOj7Fa1p4S71Lrr6tfpM/pqayVfWWOtbYH5UvlHbfo5S3PVmAlRORcF3OPOwO/6CBtYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PSrFXcOB; 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="PSrFXcOB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20DE7C116D0; Mon, 23 Feb 2026 12:37:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771850270; bh=DARLU9PRhXEqGMQEgxyxiRXMnp76keYf4PJl96EYaKs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PSrFXcOBdPDtdo5nUAH+LOaB1CfOxO7vX9jVipuRsIZ1nUGxfwdFTaaOG6stVvcE2 0wF+wzuOxTxznVHAFQrFaJoM7V/aRTnF5KlojAQtOvOfzQtq07V4gUVC7zz3cX2a8n xNE41tiTp/UeO6fU3/UPG7EL4GQIZSjraWF2jZ1tYDPNYO4q8m96/D62FiJNczqNC0 7ZEzwgLdwXxrk2OCdBB2La/XXsCmGsKoZxMA1jX2OMVN2rMmy0p18HqsmmkCe4x8L8 Uoar8qO1ie4cockybEzDjIVu9MwYLvZjZDOsUfVoukvYCrUBuxTSD456Q3R1zF14K+ czVr47KVLheLQ== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Arnd Bergmann , Catalin Marinas , Dev Jain , Will Deacon , Sasha Levin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 6.19-6.12] arm64: hugetlbpage: avoid unused-but-set-parameter warning (gcc-16) Date: Mon, 23 Feb 2026 07:37:12 -0500 Message-ID: <20260223123738.1532940-7-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260223123738.1532940-1-sashal@kernel.org> References: <20260223123738.1532940-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.19.3 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arnd Bergmann [ Upstream commit 729a2e8e9ac47099a967567389cc9d73ef4194ca ] gcc-16 warns about an instance that older compilers did not: arch/arm64/mm/hugetlbpage.c: In function 'huge_pte_clear': arch/arm64/mm/hugetlbpage.c:369:57: error: parameter 'addr' set but not used [-Werror=unused-but-set-parameter=] The issue here is that __pte_clear() does not actually use its second argument, but when CONFIG_ARM64_CONTPTE is enabled it still gets updated. Replace the macro with an inline function to let the compiler see the argument getting passed down. Suggested-by: Catalin Marinas Signed-off-by: Arnd Bergmann Reviewed-by: Dev Jain Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: ## Analysis ### What the commit does This commit replaces a `__pte_clear` macro with an equivalent inline function to fix a gcc-16 build warning/error: **Old (macro):** ```c #define __pte_clear(mm, addr, ptep) \ __set_pte(ptep, __pte(0)) ``` **New (inline function):** ```c static inline void __pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { __set_pte(ptep, __pte(0)); } ``` The two are functionally identical. The only difference is that the inline function form allows the compiler to understand that `mm` and `addr` are intentionally unused parameters passed through to satisfy the interface, suppressing the `-Werror=unused-but-set-parameter` warning that gcc-16 newly introduces. ### Classification: Build Fix This is a **build fix** — it prevents compilation failure with gcc-16 when `-Werror` is enabled. Build fixes are explicitly listed as acceptable stable material in the stable kernel rules. ### Risk Assessment **Risk: Extremely low.** The macro-to-inline-function conversion produces identical compiled output. The function body is identical (`__set_pte(ptep, __pte(0))`), and the compiler will inline it, making the generated code exactly the same. There is zero behavioral change at runtime. ### Scope - **1 file changed** (`arch/arm64/include/asm/pgtable.h`) - Small, surgical change — macro removed, inline function added in appropriate location - No logic changes whatsoever ### Considerations Against Backporting - **gcc-16 is very new** — most stable kernel users and enterprise distributions won't use it for some time - This is not a runtime bug — it only affects compilation - The warning only becomes an error with `-Werror=unused-but-set- parameter` (which gcc-16 enables by default or through `-Werror`) ### Considerations For Backporting - Build fixes are explicitly listed as stable-worthy in stable kernel rules - The change is **zero risk** — functionally identical - As distributions and users adopt gcc-16, they will hit this on older kernels - Already reviewed and accepted by arm64 maintainers (Reviewed-by: Dev Jain, Signed-off-by: Will Deacon) ### Verification - Verified the old macro and new inline function are functionally identical by reading the diff — both call `__set_pte(ptep, __pte(0))` and discard `mm` and `addr` - Verified this is purely a build fix with no runtime behavioral change - The commit message clearly describes the gcc-16 warning/error and the solution - The commit has proper review chain (Suggested-by: Catalin Marinas, Reviewed-by: Dev Jain, Signed-off-by: Will Deacon — all arm64 maintainers/reviewers) - Could NOT verify whether stable trees already have other gcc-16 build fixes (unverified, but irrelevant to the merits of this specific fix) ### Conclusion This is a zero-risk build fix that prevents compilation failure with gcc-16. While gcc-16 is new and most stable users won't encounter this immediately, the change is so low-risk (functionally identical macro-to- inline conversion) that the benefit of proactively fixing compilation clearly outweighs the negligible risk. Build fixes are explicitly called out as stable material. **YES** arch/arm64/include/asm/pgtable.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 64d5f1d9cce96..5ab5fe3bef25e 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -179,8 +179,6 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys) __pte(__phys_to_pte_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)) #define pte_none(pte) (!pte_val(pte)) -#define __pte_clear(mm, addr, ptep) \ - __set_pte(ptep, __pte(0)) #define pte_page(pte) (pfn_to_page(pte_pfn(pte))) /* @@ -1320,6 +1318,13 @@ static inline bool pud_user_accessible_page(pud_t pud) /* * Atomic pte/pmd modifications. */ + +static inline void __pte_clear(struct mm_struct *mm, + unsigned long addr, pte_t *ptep) +{ + __set_pte(ptep, __pte(0)); +} + static inline int __ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long address, pte_t *ptep) -- 2.51.0