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 EF33C3F99E6; Fri, 26 Jun 2026 14:58:42 +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=1782485925; cv=none; b=HxsMPTsnonP2t28FwgykhEIirSt8906oV1VgARq4IJ2JsKmKLYAB+9XLLvf7B3uowH8S76Z+4m0IQpHJaFl9qV+8vw6quifb2xsWPla7KreosbuyngWdkNcDdE8dop4ghucwXt4oa0LsS+VhtyrJ97fw7PWIYTzNfhb/FaDpwvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782485925; c=relaxed/simple; bh=RBbs5ttu5HZ4vWiXFFONHRCPjB4mHfKSNgMF6aWKiZU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DcHOT4LS/cD0u5nhIsBGKhOyUFZuYYV8aBu7vVvbZgWXsmPx0npyQ/7Uf/0SZYYt5hz+HeolHkwIZINJAIsXnomK4ao2Fxcw3i+s8C1UT682+LkEe79AEbD1WwVxvPXqN9dOe8f5EUfy7sOT/DSRfQjNPrEkDCQZXmOEteaSdsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XGx0mk71; 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="XGx0mk71" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD4C11F000E9; Fri, 26 Jun 2026 14:58:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782485922; bh=8cRwKyfFZJ0EQEF/mdND2222DVxVFFu/qyvWvBnTmHA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=XGx0mk71MoGFUASSSl3buSS7F0314DQL/VMMD/k7pfr9trKWTQrllQ2sXVdh3aYOY ANPzhJJsj5R2ZhQEM9A6l9eGujarHVCxjQnq8oP5RZvga5BcuuxDrJQKZOd1Mxr/56 P5FDaT6+OZ4qMSnP1GIsKRaNbewajq8aLlOXUWkrLAuiMYfd2OYbF24M+AtHrNVDrL BN3hcEPLsHV4FLsQ3p8EnCV6n9+yoofM01oDHVmcU/LrS3CZ47xVKbERnEShMuKdVw cTT2MFiDf71KrPOBRT3r1Lx8wIpztwbzWzVjAIre6N0ydk0o2ZN9DjwUB4IkHiFONw NNDs2qsYd47zg== Message-ID: Date: Fri, 26 Jun 2026 16:58:19 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 01/16] set_memory: set_direct_map_* to take address To: Brendan Jackman , Lorenzo Stoakes , "Kalyazin, Nikita" Cc: "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "linux-riscv@lists.infradead.org" , "pbonzini@redhat.com" , "corbet@lwn.net" , "maz@kernel.org" , "oupton@kernel.org" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "will@kernel.org" , "seanjc@google.com" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "luto@kernel.org" , "willy@infradead.org" , "akpm@linux-foundation.org" , "lorenzo.stoakes@oracle.com" , "vbabka@kernel.org" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "haoluo@google.com" , "jolsa@kernel.org" , "jhubbard@nvidia.com" , "jannh@google.com" , "pfalcato@suse.de" , "skhan@linuxfoundation.org" , "riel@surriel.com" , "ryan.roberts@arm.com" , "jgross@suse.com" , "yu-cheng.yu@intel.com" , "kas@kernel.org" , "coxu@redhat.com" , "ackerleytng@google.com" , "yosry@kernel.org" , "ajones@ventanamicro.com" , "maobibo@loongson.cn" , "prsampat@amd.com" , "wu.fei9@sanechips.com.cn" , "mlevitsk@redhat.com" , "jthoughton@google.com" , "agordeev@linux.ibm.com" , "alex@ghiti.fr" , "aou@eecs.berkeley.edu" , "borntraeger@linux.ibm.com" , "chenhuacai@kernel.org" , "baolu.lu@linux.intel.com" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "palmer@dabbelt.com" , "pjw@kernel.org" , "shijie@os.amperecomputing.com" , "svens@linux.ibm.com" , "thuth@redhat.com" , "Liam.Howlett@oracle.com" , "urezki@gmail.com" , "zhengqi.arch@bytedance.com" , "pavel@kernel.org" , "yangyicong@hisilicon.com" , "vannapurve@google.com" , "jackmanb@google.com" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" References: <20260410151746.61150-1-kalyazin@amazon.com> <20260410151746.61150-2-kalyazin@amazon.com> 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 6/26/26 16:38, Brendan Jackman wrote: > On Tue Apr 21, 2026 at 2:43 PM UTC, Lorenzo Stoakes wrote: >> On Fri, Apr 10, 2026 at 03:17:58PM +0000, Kalyazin, Nikita wrote: >>> From: Nikita Kalyazin >>> >>> Let's convert set_direct_map_*() to take an address instead of a page to >>> prepare for adding helpers that operate on folios; it will be more >>> efficient to convert from a folio directly to an address without going >>> through a page first. > > Why is this more efficient? Isn't it a purely compile-time conversion? > > Indeed in the current implementation folio_address() is > page_address(&folio->page) so it still goes through a page anyway, no? > > I might be missing context here about how this will look in the > memdesc future. Good question. page_address() is really only complicated for highmem. For non-highmem stuff it's simply derived from the page pfn. I suspect going page -> pfn will remain as efficient as it currently is (with vmemmap). For odd cases (SPARSEMEM without VMEMMAP) going through folio->pfn [1] might be slighty faster. [1] https://kernelnewbies.org/MatthewWilcox/Memdescs/Path -- Cheers, David