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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 6ADD5E77188 for ; Mon, 6 Jan 2025 10:02:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TBOa3jtjw6o8r0ebY72lZHoS05QVgpeUFsaHsIZ8HAU=; b=EjxgA+3aQepsp3s9QEjYRLP+Gw cKFnKlo4puzlnhc/taEQz6uCIqQa/fZhhaDhHHLcO4RsVJKfqkUYWcP7t5aeYdi0d5A7witsL/TAX 6LtEiZcZuAOu5UJqLKVfdqB41oP9W+LCXTg4mO882HD44yhl2CQJFi/iWZcGtugDLoT4McL0or+IO Svk5UwidONdPU7KMOlMA1tXGx93LRZjqYA0Jp1ZTKUc1YsCL8ZHXwg1Vt0lA/ylsefc8PHYGpPtm7 pj5t8M8Ax1oJHoVnYBZ9toH3ukRADnAohEl2r9Mvs1Lkt21zPMhEqtKRkBn9IMrlEZH2l+IbMDBOM dRF9Uisg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tUjwV-00000000mgH-483x; Mon, 06 Jan 2025 10:02:39 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tUju8-00000000m1W-1iWL for linux-nvme@lists.infradead.org; Mon, 06 Jan 2025 10:00:13 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 605C167373; Mon, 6 Jan 2025 11:00:03 +0100 (CET) Date: Mon, 6 Jan 2025 11:00:02 +0100 From: Christoph Hellwig To: Damien Le Moal Cc: Christoph Hellwig , Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Keith Busch , Sagi Grimberg , Ming Lei , Nilay Shroff Subject: Re: [PATCH 2/3] block: Fix __blk_mq_update_nr_hw_queues() queue freeze and limits lock order Message-ID: <20250106100002.GA20647@lst.de> References: <20250104132522.247376-1-dlemoal@kernel.org> <20250104132522.247376-3-dlemoal@kernel.org> <20250106083014.GD18408@lst.de> <30064337-9fe1-47c7-b4ec-c999b06a1b47@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <30064337-9fe1-47c7-b4ec-c999b06a1b47@kernel.org> 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-20250106_020012_594224_DCF6DA7D X-CRM114-Status: GOOD ( 18.89 ) 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: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Jan 06, 2025 at 06:58:00PM +0900, Damien Le Moal wrote: > Ah, yes, that would potentially be an issue... Hmmm... Maybe a better solution > would be to move the start update out of the main loop and do it first, before > the freeze. What I do not fully understand with the code of this function is > that it does freeze and limit update for each tag list of the tag set, but > there is only a single request queue for all of them. So I am confused. Why > does the blk_mq_freeze_queue and poll limit setting have to be done in the loop > multiple times for each tag list ? I do not see it... If we can move these out > of the tag list loops, then correcting the ordering becomes easy. I've come up with a version that simply never updates the flag. About to send it out.