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 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 7E219C07E99 for ; Mon, 5 Jul 2021 16:34:29 +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 9A60861946 for ; Mon, 5 Jul 2021 16:34:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A60861946 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.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=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=2YFt0Um0gDMhncgCj/U7liAaj2UDBodUl/+VLyRt52s=; b=kcbkMq5h+le/R9 5bzB8A7Q57S0OZsAh4c//k8MUX7U1TuuxbhqyHNlW2HJ9xAK0Ou2n6IVyUqeGAGBeCGInsGlt8/TI qSQLYfOmmIvM2uFVtNnG6xAIyVlUuOWuomcbir0dp+9VbR11hzW/3BcIElq0MQQiHaD1YtYWtFVFL VKUWTbL6zEnsx2CazslQpVA1ehK2vDXBYs7Lg8DPZUUO66vlKSYBded6PVZCzGK4nQGKLgs/a1DDg GFJTrNEwxAEwuYD0iTSdhAtOA3z14VRJ7AMqKLTsQyOQJVCIjFeVWaaJa4iW2vvJkGy6y4IRp4u5M RowyYTWczpkxg7n/JzMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0RY3-009VOM-7r; Mon, 05 Jul 2021 16:34:19 +0000 Received: from smtp-out2.suse.de ([195.135.220.29]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0RXz-009VNC-Ng for linux-nvme@lists.infradead.org; Mon, 05 Jul 2021 16:34:17 +0000 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id BEF7D203A4; Mon, 5 Jul 2021 16:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1625502840; h=from:from:reply-to: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=rkPXIuH/RB2D0QQyUgwo3tt0LzV1ZF0yIHcY5Q7RSRA=; b=dhQONS9SP70K9gmKDN1/3brZ6Ws7J1+ecCqYz1p2GG0YG03FI4IH6fHwbmokt1r7ya3LId AUAuMzuTQ1/kI9JaHFTNlp8unvQ08SuWzPI4I6hDly31837s4vo/g+/oW2PHbrvdh9MEHq ZmGICP3Tky5YTT10yU+K0fySIxa8VhI= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1625502840; h=from:from:reply-to: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=rkPXIuH/RB2D0QQyUgwo3tt0LzV1ZF0yIHcY5Q7RSRA=; b=GGH+zTrRWKqliCGxDTsieZ7pw98QA3b+Ipk/dEoTlWDBiCIN9d3s6+/5TX9pX0HKT9m8iL Gp8GOJBB2wgUfdCw== Received: from localhost (unknown [10.163.25.122]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 98709A3BA8; Mon, 5 Jul 2021 16:34:00 +0000 (UTC) Date: Mon, 5 Jul 2021 18:34:00 +0200 From: Daniel Wagner To: Ming Lei 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: <20210705162519.qqlklisxcsiopflw@beryllium.lan> References: <20210625101649.49296-1-dwagner@suse.de> <20210625101649.49296-3-dwagner@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210705_093415_965664_E33DE742 X-CRM114-Status: GOOD ( 14.17 ) 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 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. 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. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme