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([2601:647:4802:9070:541c:8b1b:5ac:35fe]) by smtp.gmail.com with ESMTPSA id n25sm19626442pff.51.2020.07.28.09.27.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Jul 2020 09:27:27 -0700 (PDT) Subject: Re: [PATCH] nvme-rdma: fix deadlock when delete ctrl due to reconnect fail To: James Smart , Chao Leng , linux-nvme@lists.infradead.org References: <20200727080926.30776-1-lengchao@huawei.com> <9e6242b2-fc04-632d-0ea4-7ca877c5da2c@grimberg.me> <1288e338-9e92-eeeb-6f7b-86590c6e1a4c@broadcom.com> From: Sagi Grimberg Message-ID: Date: Tue, 28 Jul 2020 09:27:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1288e338-9e92-eeeb-6f7b-86590c6e1a4c@broadcom.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200728_122729_800750_2840CF8D X-CRM114-Status: GOOD ( 13.23 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org >>> The io will do not fail. If work with native multipath or dm-multipath, >>> nvme_rdma_queue_rq will return io error, and then multipath will >>> fail over to other path and retry io, this is we expected. If work >>> without multipath, nvme_rdma_queue_rq will return BLK_STS_RESOURCE, >>> and then the upper layer will requeue and retry. Surely there is a >>> weakness:the io will retry repeated every BLK_MQ_RESOURCE_DELAY(3ms) >>> while reconnecting. Because controller reset may need long time, >>> and nvme over roce is mainly used with multipath software, so when >>> controller reset we expect fail over to other path and retry io,, just >>> like error recovery. If work without multipath, we tolerate repeated >>> I/O retries during error recovery or controller reset. >> >> I/O should not fail during reset, mpath or not, period. > > except when marked as an internal io (one used for reconnect, or maybe > an ioctl) or marked for mpath. I meant normal fs I/O, from the user perspective. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme