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 6A12AC83F10 for ; Mon, 7 Jul 2025 14:39:16 +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=SaehXI4Yj+mX7Q/ewkFy7NXRCp+vOjHdcTDQWOXjBqg=; b=Fl+8/Q0JjEKnulj19AuHbsEJQ3 8z4FVTkdA32cYLUK2rPcFkd8vytUJv6qUb9iHDB+u6fUKhm6NVQ9QvAeQ0cH3+QlNGP0b/YQIeJ0q PC0MqCktj6p/ZDyO39d7PDoo+h1N1zpWx4qVZSHdRZwUiGVknstDQNh1rePbIwFsw3UKuY0HzdnUV Dm6y6vf7VtvNEKVA0yaHqBTP8UTjvQ/59/AE2xUaeU1zOXQN0g8a3tjx0RNHUuE5KFToTKji6vSwg ujRBIJzGEGjAxCc0vGsngvHbEok8PV0UxVENDRQmX5JxNF9jGRKJEmVDtwVW+S/Z+u9LtB3yyFjxs J+RZy1Zw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYmzx-00000002jXF-1ihe; Mon, 07 Jul 2025 14:39:13 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYmlj-00000002glW-2BIA for linux-nvme@lists.infradead.org; Mon, 07 Jul 2025 14:24:32 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id EC9BC43A74; Mon, 7 Jul 2025 14:24:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71860C4CEE3; Mon, 7 Jul 2025 14:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751898270; bh=Pe0Mos0PMM22VufbyPJTrr0R+UR662fysYzPLzi8JD8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AcOEGt7l2Mn3kkpMNxemia37CEyOQSsyo69Q/e4Y1jK2rJYfTyVqZhZlvZm3WLC7Y G70jXepNmc3yY891EivmFRunF89p+VKzTq76zeggA+Y/Bb01Xp5DImfT/480ATs4Ok 8PdbyaseQhChfkk3D0dvCuskgz7+gCzBc12fDmMz4UDEQtBWHKd5z+UYye66OaJK4P IAiVwm9EmLcqS+Se7HCUl7UlPciZCwzOUiRcdo9eep27CwGElkHleIljjNzFwRThe5 FJRPeEkR4YSLelgVJZgntfe2prfzJWY8XEk2DMnp8VZysyzBK5DCdKN+vTpQJz0tiQ wH/86rjj8r7JQ== Date: Mon, 7 Jul 2025 08:24:28 -0600 From: Keith Busch To: Christoph Hellwig Cc: 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: <20250707141834.GA30198@lst.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250707_072431_575903_6AAC2C3F X-CRM114-Status: GOOD ( 15.47 ) 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 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.