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[84.110.32.226]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f258b4314sm11408949f8f.9.2025.02.17.00.08.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Feb 2025 00:08:03 -0800 (PST) Message-ID: Date: Mon, 17 Feb 2025 10:08:01 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nvme: remove multipath module parameter To: John Meneghini , kbusch@kernel.org, hch@lst.de Cc: bmarzins@redhat.com, Bryan Gurney , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Marco Patalano , axboe@kernel.dk References: <20250204211158.43126-1-bgurney@redhat.com> <7c588344-f019-4939-8a93-0a450481d4bc@redhat.com> Content-Language: en-US From: Sagi Grimberg In-Reply-To: <7c588344-f019-4939-8a93-0a450481d4bc@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 13/02/2025 22:37, John Meneghini wrote: > Keith, Christoph and Sagi, > > This patch has been fully tested and analyzed by Red Hat's QA group > and no > unexpected side effects or regressions have been found. Both NVMe/FC > and NVMe/TCP > have been tested. Our QE engineer has asked me to report this upstream. > > Tested-by: Marco Patalano > > Fixes: 32acab3181c7 ("nvme: implement multipath access to nvme > subsystems") > > As discussed in previous email threads, the nvme.core_multipath > parameter was included > by Christoph in the original implementation of nvme/host/multipath.c > back in 2017 > at the request of Red Hat. At that time Red Hat was only supporting > DMMP multipath > with NVMe and we needed a way to disable core native nvme multipathing > without > reconfiging the kernel. > > The nvme.core_multipath parameter has been used by Red Hat, together > with some additional > out-of-tree changes to nvme/host/core.c, to support DMMP multipath > with NVMe since RHEL-8. > However, the plan all along has been to deprecate and remove support > for DMMP multipath with NVMe > in RHEL and to remove this parameter. This change has been advertised > and communicated to our > customers and partners, beginning with RHEL-9, through release notes > and other communications. > > In RHEL-9 we changed the default setting of this parameter from "N" to > "Y" to match the upstream > kernel and the move our customers to native nvme multipath. DMMP > multipath w/NVMe was deprecated > in RHEL-9 but still supported. Customers were still able to optionally > enabled DMMP multipath > with NVMe if they wanted, by changing this parameter, and many of them > do. > > In the (soon to be released) RHEL-10 release DMMP multipath is longer > supported with NVMe and > the out-of-tree patches needed to support DMMP multipath with NVMe > have been removed. > > Red Hat is proposing this patch to remove nvme.core_multipath > parameter from the kernel as we believe > leaving this non-supported parameter in the kernel for future releases > will only lead to confusion. > > We plan to ship this patch with RHEL-10. So it would be really good if > we could get this > change accepted and merged upstream, perhaps into v6.15. Hey John, This looks fine to me, I'm assuming this was also tested with CONFIG_NVME_MULTIPATH=n ?