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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DB74C433DB for ; Wed, 17 Mar 2021 06:59:29 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4BFDC64F89 for ; Wed, 17 Mar 2021 06:59:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4BFDC64F89 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ISP5WPH9QMWm9Tm3A0NxBeWt7JFLuXvs9wCuUIYb708=; b=bialUeW/5I93/uz02VVQQmouw TsTj6lJHkQkw4l66lEwc7OLPPisdE7Ulu4uQhzew7tndMmzOEgsxgQfMuAgk/PucLHW2JUcRkTS6A /dG8vdI6ztXuWnsJikdAykPx6xkze4IBJ/wrXc4l6TLcTrsolGXkHaqJEJMbGvZ9nUPHnCYC7ln9w vnZyYd6WQxNegmuUqghw2cmNaM7hfdOEInM0hH40xot7JLGTeJaNFOVnl3t5Prs3VqVI9XaNljpKA 5z0apZjkQRL2e551L7fCr0DJe/w1/YjQPPIcQIzb66SbXRpKoQ2+rcqTw5H5DJPs6CcaWQMprDXub BL6rfoQAw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lMQ9I-002d8q-36; Wed, 17 Mar 2021 06:59:20 +0000 Received: from verein.lst.de ([213.95.11.211]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lMQ9B-002d72-35 for linux-nvme@lists.infradead.org; Wed, 17 Mar 2021 06:59:16 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id D190668BEB; Wed, 17 Mar 2021 07:59:10 +0100 (CET) Date: Wed, 17 Mar 2021 07:59:10 +0100 From: Christoph Hellwig To: Chao Leng Cc: Sagi Grimberg , Keith Busch , linux-nvme@lists.infradead.org, Christoph Hellwig , Chaitanya Kulkarni Subject: Re: [PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs Message-ID: <20210317065910.GC14498@lst.de> References: <20210315222714.378417-1-sagi@grimberg.me> <1b2ccda9-5789-e73a-f0c9-2dd40f320203@grimberg.me> <20210316204204.GA23332@redsun51.ssa.fujisawa.hgst.com> <59f7a030-ea33-5c31-3c18-197c5a12e982@grimberg.me> <17b15849-f0f3-af61-113f-0eb717e96f0f@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <17b15849-f0f3-af61-113f-0eb717e96f0f@huawei.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210317_065913_669619_CBEC3726 X-CRM114-Status: GOOD ( 13.72 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Mar 17, 2021 at 10:55:57AM +0800, Chao Leng wrote: >>> Will it work if nvme mpath used request NOWAIT flag for its submit_bio() >>> call, and add the bio to the requeue_list if blk_queue_enter() fails? I >>> think that looks like another way to resolve the deadlock, but we need >>> the block layer to return a failed status to the original caller. Yes, I think BLK_MQ_REQ_NOWAIT makes total sense here. dm-mpath also uses it for its request allocation for similar reasons. >> >> But who would kick the requeue list? and that would make near-tag-exhaust performance stink... The multipath code would have to kick the list. We could also try to split into two flags, one that affects blk_queue_enter and one that affects the tag allocation. > moving nvme_start_freeze from nvme_rdma_teardown_io_queues to nvme_rdma_configure_io_queues can fix it. > It can also avoid I/O hang long time if reconnection failed. Can you explain how we'd still ensure that no new commands get queued during teardown using that scheme? _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme