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=-5.2 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,URIBL_BLOCKED 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 0BBE8C07E96 for ; Tue, 6 Jul 2021 07:29:45 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C34EF61206 for ; Tue, 6 Jul 2021 07:29:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C34EF61206 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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=bombadil.20210309; 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=O9sp2Nb6SzCVNgqa/qfEYd8eyjz23NYqlvEUizeCTvA=; b=DF/5UOg9phhtAW oonCLjSF0n/ng9x5qTAgktRAgLB7Udzi5TyKWMshSbggshTSHe44SBF668nfQaQ93RYXYHbm9GGd/ wFGQ+uyJLIG1oMtlOjbdI/uwKLxz6kfezhKGxHf/qg5VQNlKucNm+7kKyiSXVYCSUtCRcIjRS0SO+ uo4C98tW/bJpJQjcMbTCxTQwQARKRj1lYUQev0xMKzAYyaINgh8fVheo9lwRCrpV1h0U2xAYozEIa W7sqR2zNibhY9ec83OLdIdektLq+v2g2hE/AXWuYTNWD0/OJb+3vYGCIZXHheL7z+KEFHqL4VUqW2 IZAQ3l0FvKwnvpAAp2rg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0fWP-00AghL-6l; Tue, 06 Jul 2021 07:29:33 +0000 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0fWM-00AggI-6Y for linux-nvme@lists.infradead.org; Tue, 06 Jul 2021 07:29:32 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625556566; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=nw0P33cYxqMaEBdimkgujl5GLUpaC+SctslNj38QzXU=; b=HrfBsg54kCVcwiU0NkMb61wyzAoaa4bqVAdWKgSa0p9Lniu1YBQbp2c9DwWoZaZNva6R2L l5AAoiktX3lXNaQwJAW4vAUts7Rud46SVqhBwxBFNL7Cain4u057yNeyFbZdAmOfuPvexp ILUYse0VwGswg3Kg+SW073GpLvrY4To= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-567-qsHgqo21NZyc2_bgpJSftQ-1; Tue, 06 Jul 2021 03:29:24 -0400 X-MC-Unique: qsHgqo21NZyc2_bgpJSftQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 59F6A1932480; Tue, 6 Jul 2021 07:29:22 +0000 (UTC) Received: from T590 (ovpn-12-27.pek2.redhat.com [10.72.12.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 671C55D6A1; Tue, 6 Jul 2021 07:29:16 +0000 (UTC) Date: Tue, 6 Jul 2021 15:29:11 +0800 From: Ming Lei To: Daniel Wagner Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, James Smart , Keith Busch , Jens Axboe , Sagi Grimberg Subject: Re: [PATCH 2/2] nvme-fc: Wait with a timeout for queue to freeze Message-ID: References: <20210625101649.49296-1-dwagner@suse.de> <20210625101649.49296-3-dwagner@suse.de> <20210705162519.qqlklisxcsiopflw@beryllium.lan> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210705162519.qqlklisxcsiopflw@beryllium.lan> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210706_002930_374929_218F3FE4 X-CRM114-Status: GOOD ( 22.68 ) 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 Mon, Jul 05, 2021 at 06:34:00PM +0200, Daniel Wagner wrote: > On Tue, Jun 29, 2021 at 09:39:30AM +0800, Ming Lei wrote: > > Can you investigate a bit on why there is the hang? FC shouldn't use > > managed IRQ, so the interrupt won't be shutdown. > > So far, I was not able to figure out why this hangs. In my test setup I > don't have to do any I/O, I just toggle the remote port. > > grep busy /sys/kernel/debug/block/*/hctx*/tags | grep -v busy=0 > > and this seems to confirm, no I/O in flight. What is the output of the following command after the hang is triggered? (cd /sys/kernel/debug/block/nvme0n1 && find . -type f -exec grep -aH . {} \;) Suppose the hang disk is nvme0n1. > > So I started to look at the q_usage_counter. The obvious observational > is that counter is not 0. The least bit is set, thus we are in atomic > mode. > > (gdb) p/x *((struct request_queue*)0xffff8ac992fbef20)->q_usage_counter->data > $10 = { > count = { > counter = 0x8000000000000001 > }, > release = 0xffffffffa02e78b0, > confirm_switch = 0x0, > force_atomic = 0x0, > allow_reinit = 0x1, > rcu = { > next = 0x0, > func = 0x0 > }, > ref = 0xffff8ac992fbef30 > } > > I am a bit confused about the percpu-refcount API. My naive > interpretation is that when we are in atomic mode percpu_ref_is_zero() > can't be used. But this seems rather strange. I must miss something. No, percpu_ref_is_zero() is fine to be called in atomic mode. Thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme