From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756565AbYDRNFW (ORCPT ); Fri, 18 Apr 2008 09:05:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754495AbYDRNFG (ORCPT ); Fri, 18 Apr 2008 09:05:06 -0400 Received: from mail.windriver.com ([147.11.1.11]:57503 "EHLO mail.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753698AbYDRNFE (ORCPT ); Fri, 18 Apr 2008 09:05:04 -0400 Message-ID: <48089BCA.1090704@windriver.com> Date: Fri, 18 Apr 2008 08:02:02 -0500 From: Jason Wessel User-Agent: Thunderbird 2.0.0.12 (X11/20080227) MIME-Version: 1.0 To: Vegard Nossum CC: Ingo Molnar , Andrew Morton , tglx@linutronix.de, penberg@cs.helsinki.fi, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jmorris@namei.org, sds@tycho.nsa.gov Subject: Re: 2.6.25-mm1: not looking good References: <20080417160331.b4729f0c.akpm@linux-foundation.org> <20080417164034.e406ef53.akpm@linux-foundation.org> <20080417171413.6f8458e4.akpm@linux-foundation.org> <48080FE7.1070400@windriver.com> <20080418073732.GA22724@elte.hu> <19f34abd0804180446u2d6f17damf391a8c0584358b8@mail.gmail.com> <20080418123439.GA17013@elte.hu> <19f34abd0804180541l7b4d14a6tb13bdd51dd533d70@mail.gmail.com> In-Reply-To: <19f34abd0804180541l7b4d14a6tb13bdd51dd533d70@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 18 Apr 2008 13:01:55.0395 (UTC) FILETIME=[60D4E930:01C8A154] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vegard Nossum wrote: > On Fri, Apr 18, 2008 at 2:34 PM, Ingo Molnar wrote: > >> * Vegard Nossum wrote: >> >> > With the patch below, it seems 100% reproducible to me (7 out of 7 >> > bootups hung). >> > >> > The number of loops it could do before hanging were, in order: 697, >> > 898, 237, 55, 45, 92, 59 >> >> cool! Jason: i think that particular self-test should be repeated 1000 >> times before reporting success ;-) >> > > BTW, I just tested a 32-bit config and it hung after 55 iterations as well. > > Vegard > > > I assume this was SMP? While I had not tried it yet, my guess would have been this did not happen on a UP kernel. If it does occur on a UP kernel it means the problem is squarely between the task scheduling after the exception is handled and the kgdb state logic for re-entering the debug state after a single step exception occurs. It seems reasonable to go for 1000 iterations of this particular test to declare success as pointed out by Ingo. Previous versions of kgdb handled some of the irq + single step + cpu sync slightly differently and it is entirely possible there is a regression there. Jason. From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48089BCA.1090704@windriver.com> Date: Fri, 18 Apr 2008 08:02:02 -0500 From: Jason Wessel MIME-Version: 1.0 Subject: Re: 2.6.25-mm1: not looking good References: <20080417160331.b4729f0c.akpm@linux-foundation.org> <20080417164034.e406ef53.akpm@linux-foundation.org> <20080417171413.6f8458e4.akpm@linux-foundation.org> <48080FE7.1070400@windriver.com> <20080418073732.GA22724@elte.hu> <19f34abd0804180446u2d6f17damf391a8c0584358b8@mail.gmail.com> <20080418123439.GA17013@elte.hu> <19f34abd0804180541l7b4d14a6tb13bdd51dd533d70@mail.gmail.com> In-Reply-To: <19f34abd0804180541l7b4d14a6tb13bdd51dd533d70@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Vegard Nossum Cc: Ingo Molnar , Andrew Morton , tglx@linutronix.de, penberg@cs.helsinki.fi, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jmorris@namei.org, sds@tycho.nsa.gov List-ID: Vegard Nossum wrote: > On Fri, Apr 18, 2008 at 2:34 PM, Ingo Molnar wrote: > >> * Vegard Nossum wrote: >> >> > With the patch below, it seems 100% reproducible to me (7 out of 7 >> > bootups hung). >> > >> > The number of loops it could do before hanging were, in order: 697, >> > 898, 237, 55, 45, 92, 59 >> >> cool! Jason: i think that particular self-test should be repeated 1000 >> times before reporting success ;-) >> > > BTW, I just tested a 32-bit config and it hung after 55 iterations as well. > > Vegard > > > I assume this was SMP? While I had not tried it yet, my guess would have been this did not happen on a UP kernel. If it does occur on a UP kernel it means the problem is squarely between the task scheduling after the exception is handled and the kgdb state logic for re-entering the debug state after a single step exception occurs. It seems reasonable to go for 1000 iterations of this particular test to declare success as pointed out by Ingo. Previous versions of kgdb handled some of the irq + single step + cpu sync slightly differently and it is entirely possible there is a regression there. Jason. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org