From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91CEE16CD1D for ; Tue, 7 Jan 2025 10:25:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736245546; cv=none; b=gna7GSGl56Y2HRmqLaWE3LgcsnKgvhPayJ9AIVFJIm0SGOIkOfw08EIQwRA+AHrcQxrZ+E991/bm9Zd7WT+2B524KWInWXtkHxWHwKoPtOnZQkWXI8nzGBISCnni74dyDnzDEaQzU7fB6bG8Ku2QhCUGcivMr/7yNyzmAtVol00= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736245546; c=relaxed/simple; bh=Ltko/t9sUklM1UW/yxtw+NkoOQ3q5ebqnCUDhoIeACs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tuavbVO+m4ryC3O3lD+1a7SXPKXrI2tAmVhNy0XxEdjSl+H2A0MFXVhXdrhiRk6O0KssmdeDrYelPPly83bUBBz32elet4mtPFbMY3Sz6rluBnrw3h9D6WGszR0Xt5FzJJzrolEe/q9JnH4EkVOaLeJbDPyiQYrl/W6f1NRO++Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=evN0ua96; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="evN0ua96" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736245542; 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=g+kgv40Nv3jmk18aQH5jxbGFwIkI3jfpro4OOu8qIeE=; b=evN0ua96xetE+8cmqzShJhbfTQzOMHagFH8Ko72jr/g/MilsLaWPhv5GkBp+7DQM0jRk4I A1fdVnYAe2ToInzGfgtP7QfgRGz6xP+1xhemhL40aDy1TZXEOIWE/LbYQ3RqiH1iKulg/s 3zACI4sJRtcxqi5hApECEcSybeBJ2Lg= Received: from mx-prod-mc-05.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-580-w5dnKRt2PPm84kKWsCv9qg-1; Tue, 07 Jan 2025 05:25:36 -0500 X-MC-Unique: w5dnKRt2PPm84kKWsCv9qg-1 X-Mimecast-MFC-AGG-ID: w5dnKRt2PPm84kKWsCv9qg Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A16BB19560A3; Tue, 7 Jan 2025 10:25:32 +0000 (UTC) Received: from fedora (unknown [10.72.116.66]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 318F5195605F; Tue, 7 Jan 2025 10:25:25 +0000 (UTC) Date: Tue, 7 Jan 2025 18:25:20 +0800 From: Ming Lei To: Nilay Shroff Cc: Christoph Hellwig , Jens Axboe , Damien Le Moal , 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 Subject: Re: [PATCH 4/8] block: add a store_limit operations for sysfs entries Message-ID: References: <20250107063120.1011593-1-hch@lst.de> <20250107063120.1011593-5-hch@lst.de> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On Tue, Jan 07, 2025 at 01:21:14PM +0530, Nilay Shroff wrote: > > > On 1/7/25 12:55 PM, Ming Lei wrote: > > On Tue, Jan 07, 2025 at 07:30:36AM +0100, Christoph Hellwig wrote: > >> De-duplicate the code for updating queue limits by adding a store_limit > >> method that allows having common code handle the actual queue limits > >> update. > >> > >> Note that this is a pure refactoring patch and does not address the > >> existing freeze vs limits lock order problem in the refactored code, > >> which will be addressed next. > >> > >> Signed-off-by: Christoph Hellwig ... > > Order between freeze and ->sysfs_lock is changed, and it may cause new > > lockdep warning because we may freeze queue first before acquiring > > ->sysfs_lock in del_gendisk(). > > > On contrary, in elevator_disable() and elevator_switch() we acquire > ->sysfs_lock first before freezing the queue. I think this is a mess and > we need to fix ordering. We need to decide ordering rules. IMO, the > correct order should be to acquire ->sysfs_lock before freezing queue. > Likewise with this patch now we acquire ->limits_lock before freezing the > queue. __blk_mq_update_nr_hw_queues() freezes queue before acquiring ->syfs_lock too. So yes, it is a mess wrt. order between ->sysfs_lock and freezing queue. Thanks, Ming