From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C61FB606A31E for ; Fri, 23 Oct 2026 17:28:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=VRNOxv+1 Received: by kanga.kvack.org (Postfix) id D50986B0BB1; Fri, 23 Oct 2026 13:28:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D29E56B0BB2; Fri, 23 Oct 2026 13:28:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C65A96B0BB3; Fri, 23 Oct 2026 13:28:01 -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 A1F7E6B0BB1 for ; Fri, 23 Oct 2026 13:28:01 -0400 (EDT) Received: from smtpin21.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 2B17EC0197 for ; Fri, 23 Oct 2026 17:28:01 +0000 (UTC) X-FDA: 85354573962.21.973BC85 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf17.hostedemail.com (Postfix) with ESMTP id 7234D40005 for ; Fri, 23 Oct 2026 17:27:59 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=VRNOxv+1; spf=pass (imf17.hostedemail.com: domain of kuba@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=kuba@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1792776479; 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=jJXUDdGOUlnprTLNQ3mpD2znb8kn6x0W43UYG81DLJE=; b=2rPU9NroIZfCNQHyDgopszgpaMDKBUJHhJUhkICFpMRiWYiDJN+kxKkn1xgDQUwg/cR7hi fLtUy2kgLE6lpjiwXmU5oGn1O+Mo8FIGn1TuxaH3b8Pdp0SwiU+MSSib65BOTUcQEMzssC Lpigldx1IKFAR2egN1hHjh7vP4KYysE= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=VRNOxv+1; spf=pass (imf17.hostedemail.com: domain of kuba@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=kuba@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1792776479; b=2ISal26llY7gxi1n/SE5A6/+H7bkTqZTvGIPRfxhJhZUKToR2oLyRBeDI4jB0qz38wJC6/ PUy307zur7fIKhUvVIdQqlbzEEiDbSHsiho8HgLBg8J2W2SvmP71ev9V6vlUsXY4fq99Yg GSEwavnFEiV4eDwzO0n8+wCId6BTUBE= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9BC06429E9; Fri, 23 Oct 2026 17:27:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68DAF1F01825; Fri, 23 Oct 2026 17:27:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792776478; bh=jJXUDdGOUlnprTLNQ3mpD2znb8kn6x0W43UYG81DLJE=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=VRNOxv+1Pksyrz5HnFhBkcnpuxCnSmnXdeyB52HziAZ0BKiZZtXPxAuj93PuJc5xI 1pTqs+75q+CJrl3PdpXqmb75U0b0ztZJPlKfMeA3oNQiv6FTGN0ztfopW9p+8p+T7P ui7Qx8f3vVvVIwafvbWaB9RjhsPkzk6toCmg6ljNO/fs5AQqJlScIW/CdQo43D6NRP tJo7uzYkrsViniHWvZsVkJCO1YIV9hAIclTxvK4nIj4FUgUlALsK4u9HNWRALjqoHb Ctem5QTw0r4Gw3aGxKfIafMxkmpl9sspL0EJ5FfAFmnB/0QSTga0iibcftCdkkp4By uoxDdS6wkAlbA== Date: Fri, 23 Oct 2026 10:27:56 -0700 From: Jakub Kicinski To: Jason Gunthorpe Cc: Luigi Rizzo , "David Hildenbrand (Arm)" , Luigi Rizzo , Joerg Roedel , Will Deacon , Robin Murphy , Christoph Hellwig , Marek Szyprowski , Andrew Morton , Vlastimil Babka , "David S . Miller" , Eric Dumazet , Paolo Abeni , Greg Kroah-Hartman , "Rafael J . Wysocki" , Danilo Krummrich , Jonathan Corbet , Jesper Dangaard Brouer , Ilias Apalodimas , Willem de Bruijn , Kuniyuki Iwashima , Joshua Washington , Harshitha Ramamurthy , Saeed Mahameed , Tariq Toukan , Tony Nguyen , Przemek Kitszel , Alexander Lobakin , Michael Chan , Pavan Chebbi , iommu@lists.linux.dev, netdev@vger.kernel.org, linux-mm@kvack.org, driver-core@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC: DMA_PMD 00/22] DMA_PMD: PMD_SIZE-backed IO buffer pools Message-ID: <20261023102756.201315d7@kernel.org> In-Reply-To: <20261023145023.GH3977851@ziepe.ca> References: <20261003212241.3432303-1-lrizzo@google.com> <0cc1cac1-a500-489b-9c1b-b49598b5550b@kernel.org> <20261022201229.GH3381610@ziepe.ca> <20261023140107.GC3977851@ziepe.ca> <20261023145023.GH3977851@ziepe.ca> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7234D40005 X-Stat-Signature: 5s4uhia11tjm6pwzwuug9c787xcwxtef X-Rspam-User: X-Spam-Status: No, score=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1792776479-741929 X-HE-Meta: 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 ToEfycVF Uv0BPsC7SVY4/G9NVaXwVJZufHXnWUfLFQfxl9/Buuo99G4EsAk9xwRjuNJ8h+5lglGWp5+EjPwh/TssRM9/6J5S45ncxGwg6kc5C2nFOVzeEe/INcDBszA0McMVxKAEDYwXZ/eg1fsMcVZ4xLS8XDMGwvhKXpi2b0D/BALqrlc/xNly6xrRtKlvBvfgTg/cvWKxUY3qp2CMrRX3NDwv6PzmH/mVf6RycO9I9ErSv6x74wqvbcIUuha6zkTBTm0KIA9rnh8haB4/LotOPF+DhbbuIS7NiLirWohew+8eLctfzLtwSHeaqrlGr5W8bgYhxStJWIWNWc5PyMOEa5wLd7TE6DFoApUGFeNCPL20cU0PfyWNPYmmaOb7EVwb5EeuePcAc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Fri, 23 Oct 2026 11:50:23 -0300 Jason Gunthorpe wrote: > > Anyways, reading your next comments, are you suggesting that all > > these functionalities should be implemented as pagepool extensions? > > (2MB mappings and iommu backing, proper allocator of fragments out of larger > > pages, device-less pagepools, multi-domain mappings, pagepool > > as memory provider for skb heads, pagepool as memory provider for descriptor > > rings ?) > > netdev shouldn't be touching iommu, it can get a 2M page and map it > using the normal DMA API. AFAIK there is not such a big reason to need > any of these layering violations. They just make it easier on page > pool.. FWIW we're entirely happy on the netdev side to add this to page pool. In fact the initial RFC I posted for "page pool memory providers" was addressing this exact use case. I didn't push it forward due to low time and suspicion that IOMMU folks would prefer a more generic solution. Since then memory providers were pushed forward and merged for dmabuf, and we have netlink APIs to configure things. So adding large mappings should be SMOC.