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 CB5F51FC11F for ; Thu, 9 Jan 2025 08:16:33 +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=1736410595; cv=none; b=VqH1XnYuMaFI3JCNiiLXQNwWevIeYS/F7KbEI9JY6xsx5Rg6B/fuuSmQD33mAHfBM4TzyU7G9pPp3W3mz4/Lw27/H7DBnZ1D6XsQQNtuyfAj8LkjaD4mVeKgjYhNOgYLWN9XNCV/wgpB0R7G5mMnmLrJUDU1KWSZuzV2u2QYNhs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736410595; c=relaxed/simple; bh=r8WzzhbMd9uRlumR+jiKxG8aABvgiegFwU6aaqrcXj4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bsazrOHZgciuhTYoHAxaH1jiOmCB5rHjwrcucFKBfjHVwSPWDcXdW+lDt7lyEAZ8dhFF1awk1JH0z0CUDI1KVIRg0NjkU8YHNyd3XDrmjfQ2OXMgnJ9TiueidRzKacSryeZ+COvcXYgfiyzkS07yV80DSrkpvyMf2WU9oS99OBc= 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=LxXT3hCm; 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="LxXT3hCm" 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> 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: <20250109055810.1402918-5-hch@lst.de> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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