From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 252EC480DC9; Thu, 6 Aug 2026 17:12:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786036362; cv=none; b=k3hNH6uozU3WXLcvJCvIgfCTQZbTU4GfFZ9ksBfYoBIP77I/b4m/5T5hcacN/FSb45XDqkuaaNAQisZfS9bbHdXXUFAlfbLGMLL7Kfl41z2I3NPHSbIQBgE5sxDO6CPQHyg2bsFHZmYkfSavXh32KthmT/9e3VeCOD0YGC9LjX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786036362; c=relaxed/simple; bh=0CVtiwf8Rea49LMoUx7r0FaUR1c1SczGdyIe/liq/ho=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=KSHeGfzwUKXjUCWMgNJtBp2TqrjSZCORBSoqkbNJhuUhzZXm/Wq/3RqfBG4aBUkuZg/7uPYdmnjjPZfVB59/naMc83YCtUCYa8sp2fw3gBwPMSf1Dge9egcQIdo0bC8aQcPcZK7ybc0Y9ONzUTGGGbZDjyTR5InyyFXfZd4JAwA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c8OYpXn/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="c8OYpXn/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14BA71F000E9; Thu, 6 Aug 2026 17:12:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786036361; bh=i2yjrrVc+H/dOZF8X/JCAszDBzatuRJpY6enVbVkXDU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=c8OYpXn/lbymZWYNNGPbBk8+3HfighE8u/aLjR6Id3SpcMlVswuIxuoFT6i8+sJVG 33bgpDZK07lgJdRnLMQQM5x5OHdfGvrUlwrg07n1Vrb5Uhrfcf7XF85qEDFGTpmbzJ qifqGwAx2bDkh0NXTIgleM+IkLM3PHw2BFHX6yZMbeRqljFQbSRqJcqKkhvmOKwx4y 8hBZqfwDXrrUJpo3Surfw1/jC6G5IUWLTS95IreVfJCJJxrzmp1dOhdDQ+kcloC6rE eCHWu6iyOrudRbovBNdMtzXkfpZdjrLsc4CWBTA/u9nkgylUVc+I/jIl/BOLL8csMs 892czlr7RY3TA== From: Will Deacon To: Russell King , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Catalin Marinas , Arnd Bergmann , Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , Tianrui Zhao , Bibo Mao , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Yeoreum Yun Cc: kernel-team@android.com, Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-openrisc@vger.kernel.org Subject: Re: [PATCH RFC v2 00/20] mm: optimize unnecessary loads due to ptep_get() and friends out Date: Thu, 6 Aug 2026 18:11:50 +0100 Message-ID: <178601690203.388302.5785771709606318463.b4-ty@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260722-dummy_ptxp3-v2-0-d9e4bad31e0a@arm.com> References: <20260722-dummy_ptxp3-v2-0-d9e4bad31e0a@arm.com> Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit On Wed, 22 Jul 2026 16:30:08 +0100, Yeoreum Yun wrote: > Using ptep_get() and its counterparts in common code is suboptimal on > kernel configurations with generic compile-time folded page tables. > By default, ptep_get() and its friends expands to READ_ONCE(), > forcing the compiler to emit a load even when the value is not used afterwards. > > This issue was recently reported by Christophe Leroy [1] for ppc32 > preventing futher code conversion to ptep_get()/pmdp_get()/... helper > and the same behavior can also be observed on arm64 when built with > 2- or 3-level page tables > > [...] Applied the arm64 patch on the end to arm64 (for-next/mm), thanks! [20/20] arm64: pgtable: convert pte_present() from macro to static inline https://git.kernel.org/arm64/c/3b56ebafecc4 Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev