From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 69EC2C43327 for ; Fri, 26 Jun 2026 15:05:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 492306B0095; Fri, 26 Jun 2026 11:05:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 442CC6B0098; Fri, 26 Jun 2026 11:05:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 30A1C6B0099; Fri, 26 Jun 2026 11:05:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id EA0B36B0095 for ; Fri, 26 Jun 2026 11:05:03 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5ABE1C2399 for ; Fri, 26 Jun 2026 15:05:03 +0000 (UTC) X-FDA: 84922386486.08.145AD84 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf28.hostedemail.com (Postfix) with ESMTP id 7DEEFC0015 for ; Fri, 26 Jun 2026 15:05:01 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ka0GYafl; spf=pass (imf28.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782486301; b=KTqfRVKYMKJpjV4SeyrmmCOcCynkOiGOSY0ahe0RSldWBwstvOxENt+i9uAnv905PZyhSy iD8ylcNekIO6XLVBoE4n+DK9PaGl9wDvffz0lb+xeGpAWRJAFBeM6sjycJZWD/uioYG7kX ZArjH0Wr4a8//bCWVjSwGr7bQP65g+Y= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782486301; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Z/3t6es/Sh5NFgNAr92B/NG50RTxtozIvYYF+FgF2iA=; b=lCc7tyCPuEDsWU3zOHEeFgfvFstCZLIeJ5+rtlEttmx48Eh/utXr+EkoP1NyF2iEEh6k6s cBYXH7wFKeJ8ojBF5Bb16VApARJ2w1YyK65SM8/4b8bqUJuELu9QHuAelB6MnfNYFNXd/N FPzjJ1oiQJjQUKqpXrR0CeQOGs/U038= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ka0GYafl; spf=pass (imf28.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Mime-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782486297; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z/3t6es/Sh5NFgNAr92B/NG50RTxtozIvYYF+FgF2iA=; b=ka0GYaflSKkPFQ7rFhIGoeEDcZfUQi/jBpWMJl+inaTs6Ay8kTJp9zdbYmSenvlQJh+XR+ XB172PGZ4cpCqyqeulNT+N+xr0AurrQi4xrcP61whLGk9uJ8pOP+saDL+I6rAvgBdS3Po7 QQIlkgcah948ts7waig31URzqiuDpu0= Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 26 Jun 2026 15:04:48 +0000 Message-Id: X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Brendan Jackman" 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" , "david@kernel.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" Subject: Re: [PATCH v12 01/16] set_memory: set_direct_map_* to take address References: <20260410151746.61150-1-kalyazin@amazon.com> <20260410151746.61150-2-kalyazin@amazon.com> In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7DEEFC0015 X-Rspam-User: X-Stat-Signature: wurz4qq45er7suwspry8rftya9fn6gcq X-HE-Tag: 1782486301-793881 X-HE-Meta: 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 U7YxvhNW wUe8hib8r2pJNJmFooxkqODVSlVW+xGERg58GsJKU8QN++ivD6bUnyL0yamakOP8wFF+HzawRLkXo8T/rSAwSHQ2WQ2EbqEdBY9DD1vYpk4eqauQ6eBB7LfbZnROE45p2RKt1Io3gufITaWnpyCe1vpy7LnSvntc/+6DezBceW7xGim3swJc3Rz6ozcJY7e6TBpulFVInd6zfnGhtPzgA7LiqhGCaInu1q5LuO9x/xiKPkqS0k+Oh6E/FoT45nmZsQ2P6K3NS4Yk1gPDznXyiuTtv/kicyeZcY0DSypuM0D2ANu9K4A9ZzM1F5DKJAdRLkeYARv8y0uP0BHUP7sZ8WZNUNFGex51Z/pFAdaVkQ5CdPtWGTWbGsVywZMg9LArdGKd6tVztlmhbyPGoXXisPURIb+QrszbK/A/C8OGYb2Y6381ZPpgy5bW/w9cA/vZCD5grw/T5yFp/KH+iJaz9T9Hcs3UVGdwzgQ1/8v1DC4DOcrQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Jun 26, 2026 at 2:38 PM UTC, 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 t= o >>> 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. Sorry I failed to do the history search here, this was suggested by Willy during the review here: https://lore.kernel.org/kvm/aWkN4yzwPtotaTeq@casper.infradead.org/ Matthew Wilcox wrote: > The implementation isn't the greatest. None of the implementations > of set_direct_map_valid_noflush() actually do anything with the struct > page; they all call page_address() or page_to_virt() (fundamentally the > same thing). =20 But IMO the struct page isn't there to carry runtime information, it's a type hint that this API operates on physical pages. Yes this is already implied by the name but it also gives us a certain amount of safety since it avoids unaligned or non-physmap addresses at compile time. > So converting folio->page->address is a bit inefficient. ... but yeah now I see this comes from Willy I definitely suspect I'm missing memdesc insight here.=20 > It feels like we should change set_direct_map_valid_noflush() to take a > const void * and pass either page_address() or folio_address(), depending > whether the caller has a page or a folio. What do you think?