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[46.117.80.176]) by smtp.gmail.com with ESMTPSA id gw6-20020a05600c850600b0041273fc463csm2210845wmb.17.2024.03.07.02.35.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 Mar 2024 02:35:12 -0800 (PST) Message-ID: <5a6ceb89-c242-4e76-b6f3-91c83099794a@grimberg.me> Date: Thu, 7 Mar 2024 12:35:11 +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: fix reconnection fail due to reserved tag allocation Content-Language: en-US To: =?UTF-8?B?6K645pil5YWJ?= Cc: kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org References: <20240228091417.40110-1-brookxu.cn@gmail.com> <6eae3879-f9d2-4fe3-96b1-c9e2aa939264@grimberg.me> From: Sagi Grimberg In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 07/03/2024 12:32, 许春光 wrote: > Thanks for review, seems that we should revert this patch > ed01fee283a0, ed01fee283a0 seems just a alone 'optimization'. If no > double, I will send another patch. Not a revert, but a fix with a Fixes tag. Just use NVMF_ADMIN_RESERVED_TAGS and NVMF_IO_RESERVED_TAGS. > > Thanks > > Sagi Grimberg 于2024年3月7日周四 17:36写道： >> >> >> On 28/02/2024 11:14, brookxu.cn wrote: >>> From: Chunguang Xu >>> >>> We found a issue on production environment while using NVMe >>> over RDMA, admin_q reconnect failed forever while remote >>> target and network is ok. After dig into it, we found it >>> may caused by a ABBA deadlock due to tag allocation. In my >>> case, the tag was hold by a keep alive request waiting >>> inside admin_q, as we quiesced admin_q while reset ctrl, >>> so the request maked as idle and will not process before >>> reset success. As fabric_q shares tagset with admin_q, >>> while reconnect remote target, we need a tag for connect >>> command, but the only one reserved tag was held by keep >>> alive command which waiting inside admin_q. As a result, >>> we failed to reconnect admin_q forever. >>> >>> In order to workaround this issue, I think we should not >>> retry keep alive request while controller reconnecting, >>> as we have stopped keep alive while resetting controller, >>> and will start it again while init finish, so it maybe ok >>> to drop it. >> This is the wrong fix. >> First we should note that this is a regression caused by: >> ed01fee283a0 ("nvme-fabrics: only reserve a single tag") >> >> Then, you need to restore reserving two tags for the admin >> tagset.