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 BEFCBE77197 for ; Thu, 9 Jan 2025 08:16:37 +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=eD4PQ2lqozBCLy6ODlL7uzyXEhGgP3XjJCgY56pBPH0=; b=L7YVzcPLCCe3hLk7NgSCJAF8da V4CIyCPirnJ11MuH19r4PvX7c/emxjP8+5fp4BlE0CjwlC71dlDB/7JSRnfg+GaGBSEAL4RuT+HoW f6rZlVLeIqLMfmEubN8QhrYetCQpdsQSLWVwaK1SUqFtHgOLmchCnBL+Ri7MSJjRZGZ5yoVG/ZFq8 TsICyNPdMf41We/p7uzdTlrwDBGCJmPYMXHDJgpPCMR9t1N9/6VtvspFEG+cTE7augLtqCghMa7T0 RPnRavq+s+bFJR/BHyf2qkjTIggyG1XiWrD/0C3WX4n/cXoXPpytEWEfuuAIbQNjQNN5WJcvyLG46 g3wz3QQg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVniV-0000000B9oV-3QU6; Thu, 09 Jan 2025 08:16:35 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tVniT-0000000B9nw-2GgG for linux-nvme@lists.infradead.org; Thu, 09 Jan 2025 08:16:34 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736410592; 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=eD4PQ2lqozBCLy6ODlL7uzyXEhGgP3XjJCgY56pBPH0=; b=LxXT3hCm7W6StSLVHHPub7yW06kIk880dlBBGnvQOBSVgyZkfaC/Ntf1ThNNP126LQSWPz YgzXbck9hP4O1usRczJKduaLI5rLOo854IyB7N23eYhWabj13fK/2EWJEMMHD4BcIBusUr b3IfNCgscT46aKNEsEEY56xzeylZDkI= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-436-NkzkPsgmN0iiF3ToB2oXgQ-1; Thu, 09 Jan 2025 03:16:29 -0500 X-MC-Unique: NkzkPsgmN0iiF3ToB2oXgQ-1 X-Mimecast-MFC-AGG-ID: NkzkPsgmN0iiF3ToB2oXgQ Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EA31A1955D71; Thu, 9 Jan 2025 08:16:26 +0000 (UTC) Received: from fedora (unknown [10.72.116.139]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4B49C1955BE3; Thu, 9 Jan 2025 08:16:19 +0000 (UTC) Date: Thu, 9 Jan 2025 16:16:14 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , Damien Le Moal , Nilay Shroff , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, nbd@other.debian.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, Johannes Thumshirn Subject: Re: [PATCH 04/11] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues Message-ID: References: <20250109055810.1402918-1-hch@lst.de> <20250109055810.1402918-5-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250109055810.1402918-5-hch@lst.de> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250109_001633_648082_A7711E96 X-CRM114-Status: GOOD ( 15.73 ) 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 Thu, Jan 09, 2025 at 06:57:25AM +0100, Christoph Hellwig wrote: > When __blk_mq_update_nr_hw_queues changes the number of tag sets, it > might have to disable poll queues. Currently it does so by adjusting > the BLK_FEAT_POLL, which is a bit against the intent of features that > describe hardware / driver capabilities, but more importantly causes > nasty lock order problems with the broadly held freeze when updating the > number of hardware queues and the limits lock. Fix this by leaving > BLK_FEAT_POLL alone, and instead check for the number of poll queues in > the bio submission and poll handlers. While this adds extra work to the > fast path, the variables are in cache lines used by these operations > anyway, so it should be cheap enough. > > Fixes: 8023e144f9d6 ("block: move the poll flag to queue_limits") > Signed-off-by: Christoph Hellwig > Reviewed-by: Damien Le Moal > Reviewed-by: Johannes Thumshirn Reviewed-by: Ming Lei Thanks, Ming