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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4A810C8303F for ; Fri, 29 Aug 2025 04:44:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vCM7BtjhSSdjPD2pC7Een8DTkoaQQR4fjFPHIwA5Djs=; b=nvwRZnzL1tt8jT1W4N9eezhpip VLIscN7Wg+sDkqv7IfqZLijGgfiFBq2M+CLC3MUbYl8+bq7v+S0Zh2/MGOWPNuougrrcmcMX4yu0m Fgg9EqCeUJbfAzBoGTd20w08LC4ip3lFG5FfPw6J5zaqeEX7832a19mE8oF3hX37zHF3Ee9M+Cknr JDobwq4TBuoRc060nOreTVfgUrHvRnAr/e8PJO6XLKDOmws7WiiYPBjRFJSb13np73kvO6m16UbN+ Xn1gs6PoTuATD7MT4TCKqc4o3OJSVLDfTU929wJiUTG0jt1TIam2XBJEgwIr+tZl2/6r+jnvHeLRF EjY95hWQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1urqyj-00000004PcG-1cOM; Fri, 29 Aug 2025 04:44:45 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uri17-00000002wcI-1dHm for linux-nvme@lists.infradead.org; Thu, 28 Aug 2025 19:10:37 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id AE2F160139; Thu, 28 Aug 2025 19:10:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFBADC4CEEB; Thu, 28 Aug 2025 19:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756408236; bh=nTTeahhIb0FZNTHkQNMJBnWQfHnp2aJ+r4oH3UJmf9I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kiAyKBDPTCAig6cfYhRFzVMlXt8gF/BgqIWlzfngucl4yl5Wcl8PEMxeGxZyn4feY 9QNbLauol7wPo69EnbsJUOvYSMo6YfZ3+owIkOs7tkWX5BPwXZEGC9l2iz9VL73nWJ LMeYGO+x9LIMWkAgoCM0LVxjf0/nrBlT574LedC07bLp9s3BQzVau6M5uUSf07U/m8 vqELaFQz9N5nFU8S5MsiAq/DKmR1fhhzHyINYKZV0xBuVLm5Y0saWfzSXpuLfpmwbf 9eS/h5nEcBCqmS1GS4AcOq4YDto3/XpsP6UcVeqRbKR8yG+flv5A1aPbY1iMmgWmoI HI/G0rHOVaaNA== Date: Thu, 28 Aug 2025 13:10:32 -0600 From: Keith Busch To: Jason Gunthorpe Cc: Leon Romanovsky , Marek Szyprowski , Abdiel Janulgue , Alexander Potapenko , Alex Gaynor , Andrew Morton , Christoph Hellwig , Danilo Krummrich , iommu@lists.linux.dev, Jason Wang , Jens Axboe , Joerg Roedel , Jonathan Corbet , Juergen Gross , kasan-dev@googlegroups.com, linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nvme@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, Madhavan Srinivasan , Masami Hiramatsu , Michael Ellerman , "Michael S. Tsirkin" , Miguel Ojeda , Robin Murphy , rust-for-linux@vger.kernel.org, Sagi Grimberg , Stefano Stabellini , Steven Rostedt , virtualization@lists.linux.dev, Will Deacon , xen-devel@lists.xenproject.org Subject: Re: [PATCH v4 15/16] block-dma: properly take MMIO path Message-ID: References: <642dbeb7aa94257eaea71ec63c06e3f939270023.1755624249.git.leon@kernel.org> <20250828165427.GB10073@unreal> <20250828184115.GE7333@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250828184115.GE7333@nvidia.com> X-Mailman-Approved-At: Thu, 28 Aug 2025 21:42:14 -0700 X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Aug 28, 2025 at 03:41:15PM -0300, Jason Gunthorpe wrote: > On Thu, Aug 28, 2025 at 11:15:20AM -0600, Keith Busch wrote: > > > > I don't think that was ever the case. Metadata is allocated > > independently of the data payload, usually by the kernel in > > bio_integrity_prep() just before dispatching the request. The bio may > > have a p2p data payload, but the integrity metadata is just a kmalloc > > buf in that path. > > Then you should do two dma mapping operations today, that is how the > API was built. You shouldn't mix P2P and non P2P within a single > operation right now.. Data and metadata are mapped as separate operations. They're just different parts of one blk-mq request.