From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756412AbbFQLwo (ORCPT ); Wed, 17 Jun 2015 07:52:44 -0400 Received: from 8bytes.org ([81.169.241.247]:47695 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755693AbbFQLwk (ORCPT ); Wed, 17 Jun 2015 07:52:40 -0400 Date: Wed, 17 Jun 2015 13:52:39 +0200 From: Joerg Roedeljoro To: =?utf-8?B?6IyD5Yas5Yas?= Cc: linux-kernel , "jiang.liu@intel.com" , iommu , =?utf-8?B?6Zer5pmT5bOw?= , =?utf-8?B?5YiY6ZW/55Sf?= Subject: Re: Panic when cpu hot-remove Message-ID: <20150617115238.GC27750@8bytes.org> References: <42BB8332972FC149B81C55A0D41E3A79C07469@jtjnmailbox06.home.langchao.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <42BB8332972FC149B81C55A0D41E3A79C07469@jtjnmailbox06.home.langchao.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 17, 2015 at 10:42:49AM +0000, 范冬冬 wrote: > Hi maintainer, > > We found a problem that a panic happen when cpu was hot-removed. We also trace the problem according to the calltrace information. > An endless loop happen because value head is not equal to value tail forever in the function qi_check_fault( ). > The location code is as follows: > > > do { > if (qi->desc_status[head] == QI_IN_USE) > qi->desc_status[head] = QI_ABORT; > head = (head - 2 + QI_LENGTH) % QI_LENGTH; > } while (head != tail); Hmm, this code interates only over every second QI descriptor, and tail probably points to a descriptor that is not iterated over. Jiang, can you please have a look? Joerg