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 4CA9043A7E1; Wed, 15 Jul 2026 09:43:38 +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=1784108628; cv=none; b=Jmb75ZWSLREpgjrDGwRJ4cvSb/aHEPUZx4SDxpMgxaMNDrj9hVEyt1xlbc3UIHtRGMD7LMvNyERXftLc8UVQn44441X531aWNWEErnwLW+y5hE/iTZ3avXYGoLKbx17cfXCl7P2+1anh27hSKwmBv0M2kAhKlTYRj+wx2WSp9ig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784108628; c=relaxed/simple; bh=u3wwU/z4C89zqWRgwncGfnBh+kphBpJ0n+qjY6S/8oY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=U9+3+tQxqf0vhSiK+sRm55Nj0OtOSVkp1rOpZhLGxJ5AqfYVE+1NVhnJk9Dr0C3KyVMtpLAHdV/SRIXdUi4i9cMCayU3PdizLXsw0g3IGX84+tWvnFaxYYhdqDsqMlWDuc+SuBYke/90OJurAonqNRvkQJbr8eQKtXnBFlMyv6g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DBliIrs1; 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="DBliIrs1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 464261F000E9; Wed, 15 Jul 2026 09:43:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784108616; bh=CC+e/Z0BaeZIfuy0GA+8f2VQ0SUjP7mL+FiN+wpHZDM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DBliIrs1Vie421HB7pFithfaf6+UeS3O6z2aoh/aN1WWGPjXflmiUACQdZ3xpskBY xMfYSp2UqXDvXFvK55J+NuyWH3rQs+JwYDOnaQ0FnmpRHN6bsvs75KwaUdohNozQJj XSf940SX0+vO09aO3jHGkAXGyO7J8nwLLVm3PGMTkrAf2Uj/RNJe0WW9mYrpDx4w16 2hht1+fq5ju7pSYbsa+Git3edPTDAqecJ+sV2mJ0+WNWq7ptmUxMNEQvPoQ3QcSlCp m9Teaq/0qIGpP303+Rl9w/iFPHMOESoof6nsGY/ZidS26od+bMOS/kWhVtaM7LyALb j4kx/9RfCKujg== Message-ID: <14019379-1725-4cad-8158-322714b19ace@kernel.org> Date: Wed, 15 Jul 2026 11:43:20 +0200 Precedence: bulk X-Mailing-List: linux-csky@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 10/34] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot() To: Yeoreum Yun Cc: Dave Hansen , 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, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux@armlinux.org.uk, akpm@linux-foundation.org, ankur.a.arora@oracle.com, rppt@kernel.org, linmag7@gmail.com, chleroy@kernel.org, klarasmodin@gmail.com, chenhuacai@kernel.org, kernel@xen0n.name, kas@kernel.org, zhangtianyang@loongson.cn, wangyuli@aosc.io, tsbogend@alpha.franken.de, ljs@kernel.org, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, ryan.roberts@arm.com, pasha.tatashin@soleen.com, rmclure@linux.ibm.com, baolin.wang@linux.alibaba.com, tj@kernel.org, kevin.brodsky@arm.com, anup@brainfault.org, atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, hannes@cmpxchg.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, anshuman.khandual@arm.com, yang@os.amperecomputing.com, chaitanyas.prakash@arm.com, ardb@kernel.org, guoren@kernel.org, yang.li85200@gmail.com, viro@zeniv.linux.org.uk, dinguyen@kernel.org, schuster.simon@siemens-energy.com, wangruikang@iscas.ac.cn, junhui.liu@pigmoral.tech, muchun.song@linux.dev, vishal.moola@gmail.com, namcao@linutronix.de, pavel@kernel.org, djbw@kernel.org, yu-cheng.yu@intel.com, baolu.lu@linux.intel.com, Jonathan.Cameron@huawei.com, coxu@redhat.com, andreas@gaisler.com, liam@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, geert@linux-m68k.org, shorne@gmail.com, jonas@southpole.se, stefan.kristiansson@saunalahti.fi References: <32d459d1-ad19-4baf-bbb1-0565458001d2@intel.com> <3ea30f8a-bb29-4bf5-8400-1c4840d46a88@kernel.org> <7e84b200-25eb-43a6-b5e2-5f27f2d82a77@intel.com> <31988089-095a-4eed-b5e2-c677c70f79f6@kernel.org> <14e250db-1641-4085-8d13-02f819657d5f@intel.com> <6df814c9-405c-48d8-96ea-929c4b28949b@intel.com> <2d51a1ad-85be-46bf-ac36-18eca199b449@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/14/26 20:28, Yeoreum Yun wrote: > On Tue, Jul 14, 2026 at 06:31:22PM +0200, David Hildenbrand (Arm) wrote: >> >>> >>> Agree. Calling a pXd_entry() about folded one seems meaningless. >>> But seems enough to check mm_pXd_folded() before calling pXd_entry() >>> in each walk_pXd_range(). >> >> Needs some double-checking that callers can handle it (like effective_prot() >> would currently not), but certainly something to look into! > > Most of mm_walk_ops *implicitly* handles the folded pgtable case > (e.x) pXd_none() / pXd_present() and other can handle explicitly in > its own handler. > > But, IMHO, It would be better to skip calling pXd_entry() in the > walk_pXd_range() by checking the folded and this is clearer conceptually. > > For this, it requires the rewrite the walk_mm() where use only *p4d_entry()* > to gather the leaf/non-leaf information for MGLRU. Yeah, this needs a thought indeed. -- Cheers, David