Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750793AbWEWQCo (ORCPT ); Tue, 23 May 2006 12:02:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750795AbWEWQCo (ORCPT ); Tue, 23 May 2006 12:02:44 -0400 Received: from ms-smtp-02.nyroc.rr.com ([24.24.2.56]:26302 "EHLO ms-smtp-02.nyroc.rr.com") by vger.kernel.org with ESMTP id S1750793AbWEWQCn (ORCPT ); Tue, 23 May 2006 12:02:43 -0400 Subject: Re: Ingo's realtime_preempt patch causes kernel oops From: Steven Rostedt To: Daniel Walker Cc: Yann.LEPROVOST@wavecom.fr, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar In-Reply-To: <1148398425.3535.92.camel@c-67-180-134-207.hsd1.ca.comcast.net> References: <1148393971.4997.24.camel@localhost.localdomain> <1148398425.3535.92.camel@c-67-180-134-207.hsd1.ca.comcast.net> Content-Type: text/plain Date: Tue, 23 May 2006 12:02:18 -0400 Message-Id: <1148400138.21012.6.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.4.2.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2347 Lines: 63 On Tue, 2006-05-23 at 08:33 -0700, Daniel Walker wrote: > On Tue, 2006-05-23 at 10:19 -0400, Steven Rostedt wrote: > > > > > The fault is at 0x40 and looking at profile_tick it calls > > user_mode(regs). user_mode(x) is defined in arm as > > (((regs)->ARM_cpsr & 0xf) == 0) > > > > And ARM_cpsr is uregs[16] So if arm has 4 byte words and regs was NULL, > > it would fault on 16*4 = 64 or 0x40 > > > > It looks like the timer interrupt on this board is having a NULL regs > > passed to it when hard interrupts are threads. Which might mean that > > the timer interrupt is itself a thread. > > Hmm, well usually ARM timer interrupts have the SA_TIMER flag .. In > realtime ARM changes SA_TIMER includes SA_NODELAY .. > > In 2.6.17-rc4 > > arch/arm/mach-at91rm9200/time.c > > static struct irqaction at91rm9200_timer_irq = { > .name = "at91_tick", > .flags = SA_SHIRQ | SA_INTERRUPT, > .handler = at91rm9200_timer_interrupt > }; > > No SA_TIMER, and no SA_NODELAY , so i'd imagine it's is in a thread .. Yep, I would say it is. Yann, could you try the following patch to see if it makes it better for you. I added SA_NODELAY so that the timer is run in interrupt context, and removed the shared flag, because I have no idea what might share a timer interrupt, and it might cause other bugs. If something needs to share this interrupt, then we need to do something else. Since I don't have any arm boards, I cant test it, so this wasn't even compiled. -- Steve Index: linux-2.6.16-rt23/arch/arm/mach-at91rm9200/time.c =================================================================== --- linux-2.6.16-rt23.orig/arch/arm/mach-at91rm9200/time.c 2006-05-23 11:58:21.000000000 -0400 +++ linux-2.6.16-rt23/arch/arm/mach-at91rm9200/time.c 2006-05-23 11:58:45.000000000 -0400 @@ -87,7 +87,7 @@ static irqreturn_t at91rm9200_timer_inte static struct irqaction at91rm9200_timer_irq = { .name = "at91_tick", - .flags = SA_SHIRQ | SA_INTERRUPT, + .flags = SA_INTERRUPT | SA_NODELAY, .handler = at91rm9200_timer_interrupt }; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/