Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751391AbeAPCP5 (ORCPT + 1 other); Mon, 15 Jan 2018 21:15:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37632 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750740AbeAPCPz (ORCPT ); Mon, 15 Jan 2018 21:15:55 -0500 Date: Tue, 16 Jan 2018 10:15:38 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Laurence Oberman , Mike Snitzer Subject: Re: [PATCH 0/2] genirq/affinity: try to make sure online CPU is assgined to irq vector Message-ID: <20180116021537.GG3213@ming.t460p> References: <20180115160345.2611-1-ming.lei@redhat.com> <20180115174036.GA20191@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180115174036.GA20191@infradead.org> User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 16 Jan 2018 02:15:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Mon, Jan 15, 2018 at 09:40:36AM -0800, Christoph Hellwig wrote: > On Tue, Jan 16, 2018 at 12:03:43AM +0800, Ming Lei wrote: > > Hi, > > > > These two patches fixes IO hang issue reported by Laurence. > > > > 84676c1f21 ("genirq/affinity: assign vectors to all possible CPUs") > > may cause one irq vector assigned to all offline CPUs, then this vector > > can't handle irq any more. > > Well, that very much was the intention of managed interrupts. Why > does the device raise an interrupt for a queue that has no online > cpu assigned to it? If pci_alloc_irq_vectors() returns OK, driver may think everything is just fine, and configure the related hw queues(such as enabling irq on queues), and finally irq comes and no CPU can handle them. Also I think there may not drivers which check if the CPUs assigned for irq vectors are online or not, and seems never a job which is supposed to do by driver. -- Ming