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 0F1CAC8303C for ; Mon, 7 Jul 2025 15:57:02 +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=EIvTsutl8deZYlildXdukB7Zqzo7Azdoq6G919OJYf4=; b=1KmI8ua9+AUdF+pbxDOjkK6Ja0 kBqrzLrWEis02PN4cavy0CXHZiBDy7ZkvZX0aA8b3BEBKCq2uI2FCfvfMbmkIPehsGXVe2V8Oh7+t LmV/zIbzvAjfIb6ePRPxe7aQMttna5K2rcQLacDCw8PH/Ovl+gDlt5paSRTUb5MvkZGfVejBkh2iJ isyRZW2+7X7E169U1xuLjyDqXf5ypMTwLVPuZzDFLSGG6Ap9OZbsRlnObCVM8I24PSLmVrtRYrCwd AaHDoTYpX81UpYAiC57UPvtudvyB2Il30BqotY9D8khdLuqXOrgxw/OHB+mnxwnjM7a/HS8OUogkm SN6khOPg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYoDC-00000002wP1-3wwn; Mon, 07 Jul 2025 15:56:58 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYoDA-00000002wOe-1DMO for linux-nvme@lists.infradead.org; Mon, 07 Jul 2025 15:56:57 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B56685C1986; Mon, 7 Jul 2025 15:56:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 014CCC4CEE3; Mon, 7 Jul 2025 15:56:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751903815; bh=K4TsgEfbZBCaB5T+UtpxvoxOzf99yOdPJVsE+Cw+Y0k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z5AcbnHd8RRLiGwhKyQCEKRiHwDNnLOxKiGli9/0YhEm80kN3aq/ruts5qIlYk5A6 6LpG+1G1+nv05A1Wxr2wUxcViszbUUm6gRJ2PqKzMEPDftjSXMsLAnPx0t/HtgU+st aqb4rtSXW2NfYnQuUwDRBiTdswIlRVJchl73ewkVGZ+x5/szVxEYKqT3RhUV5sw1pF R6nLYOibtMPyw1r6GIReKmpLlJCUhkTQUuSks/bAkErPer/csYqicOpJusESYU0MBH v/28k6znhy+zdn7NhyN02dMIM1MVXWXuUzUAXgK81kQxg1bzeeefYX5fR8CSVJrZ7d 5OAt+Oi6Olaxw== Date: Mon, 7 Jul 2025 09:56:53 -0600 From: Keith Busch To: Hannes Reinecke Cc: Christoph Hellwig , Alan Adamson , John Garry , "Martin K. Petersen" , Jens Axboe , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org Subject: Re: What should we do about the nvme atomics mess? Message-ID: References: <20250707141834.GA30198@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250707_085656_370724_3E00FC19 X-CRM114-Status: GOOD ( 23.79 ) 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 Mon, Jul 07, 2025 at 05:26:46PM +0200, Hannes Reinecke wrote: > On 7/7/25 16:24, Keith Busch wrote: > > On Mon, Jul 07, 2025 at 04:18:34PM +0200, Christoph Hellwig wrote: > > > We could: > > > > > > I. revert the check and the subsequent fixup. If you really want > > > to use the nvme atomics you already better pray a lot anyway > > > due to issue 1) > > > II. limit the check to multi-controller subsystems > > > III. don't allow atomics on controllers that only report AWUPF and > > > limit support to controllers that support that more sanely > > > defined NAWUPF > > > > > > I guess for 6.16 we are limited to I. to bring us back to the previous > > > state, but I have a really bad gut feeling about it given the really > > > bad spec language and a lot of low quality NVMe implementations we're > > > seeing these days. > > > > I like option III. The controler scoped atomic size is broken for all > > the reasons you mentioned, so I vote we not bother trying to make sense > > of it. > > > Agree. We might consider I. as a fixup for stable, but should continue > with III going forward. I think the NVMe TWG might want to consider an ECN to deprecate or at least recommend against AUWPF, too. Just to throw AWUPF a lifeline for legecy devices, we could potentially make sense of the value if Identify Controller says: 1. CMIC == 0; and 2. OACS.NMS == 0; and 3. a. FNA.FNS == 1; or b. NN == 1 And if those conditions are true, then the controller and namespace scopes resolve to a single namespace format, so the values should be one in the same. The only way it could change, then, is a format command, which means there couldn't be an in-use filesystem depending on it not changing.