Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753457AbYL0HPV (ORCPT ); Sat, 27 Dec 2008 02:15:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751342AbYL0HPG (ORCPT ); Sat, 27 Dec 2008 02:15:06 -0500 Received: from hera.kernel.org ([140.211.167.34]:60269 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750988AbYL0HPF (ORCPT ); Sat, 27 Dec 2008 02:15:05 -0500 Message-ID: <4955D5C5.90407@kernel.org> Date: Fri, 26 Dec 2008 23:14:13 -0800 From: Yinghai Lu User-Agent: Thunderbird 2.0.0.18 (X11/20081112) MIME-Version: 1.0 To: Kamalesh Babulal CC: Ingo Molnar , Sam Ravnborg , David Howells , Andrew Morton , Stephen Rothwell , linux-next@vger.kernel.org, LKML , mel@csn.ul.ie Subject: Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask References: <495153A4.5060201@kernel.org> <20081224163400.GA11562@linux.vnet.ibm.com> <49529CE1.4040005@kernel.org> <20081226091217.GA5100@linux.vnet.ibm.com> <4954AC7B.3020603@kernel.org> <20081226102716.GA31450@uranus.ravnborg.org> <20081226152804.GB5100@linux.vnet.ibm.com> <20081226153318.GA4514@elte.hu> <20081226170452.GC5100@linux.vnet.ibm.com> <20081226181733.GA24439@elte.hu> <20081227071138.GA4530@linux.vnet.ibm.com> In-Reply-To: <20081227071138.GA4530@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3036 Lines: 105 Kamalesh Babulal wrote: > * Ingo Molnar [2008-12-26 19:17:34]: > >> * Kamalesh Babulal wrote: >> >>>> how about the patch below, does that work too? (after removing >>>> Yinghai's patch) >>> Hi Ingo, >>> >>> Kernel crashes with the same trace, after the applying the patch. >> okay, thanks - does the below cleaner variant of Yinghai's patch solve the >> problem too? >> >> Ingo >> >> --------------------> >> From 9c93fc72ec95dc97d65b840978f9d605f4e5823a Mon Sep 17 00:00:00 2001 >> From: Yinghai Lu >> Date: Fri, 26 Dec 2008 02:05:47 -0800 >> Subject: [PATCH] sparseirq: work around compiler optimizing away __weak functions >> >> Impact: fix panic on null pointer with sparseirq >> >> Some GCC versions seem to inline the weak global function, >> when that function is empty. >> >> Work it around, by putting a barrier into the function. >> >> Signed-off-by: Yinghai >> Signed-off-by: Ingo Molnar >> --- >> init/main.c | 9 +++++++++ >> kernel/irq/handle.c | 3 ++- >> 2 files changed, 11 insertions(+), 1 deletions(-) >> >> diff --git a/init/main.c b/init/main.c >> index c1f999a..841d2b2 100644 >> --- a/init/main.c >> +++ b/init/main.c >> @@ -531,20 +531,29 @@ static void __init boot_cpu_init(void) >> cpu_set(cpu, cpu_possible_map); >> } >> >> +/* >> + * The barriers are needed to keep a GCC bug from optimizing >> + * away these weak functions: >> + */ >> + >> void __init __weak smp_setup_processor_id(void) >> { >> + barrier(); >> } >> >> void __init __weak thread_info_cache_init(void) >> { >> + barrier(); >> } >> >> void __init __weak arch_early_irq_init(void) >> { >> + barrier(); >> } >> >> void __init __weak early_irq_init(void) >> { >> + barrier(); >> arch_early_irq_init(); >> } >> >> diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c >> index 06b05a4..a6d16a4 100644 >> --- a/kernel/irq/handle.c >> +++ b/kernel/irq/handle.c >> @@ -86,8 +86,9 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr) >> desc->kstat_irqs = (unsigned int *)ptr; >> } >> >> -void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu) >> +void __weak arch_init_chip_data(struct irq_desc *desc, int cpu) >> { >> + barrier(); >> } >> >> static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu) >> -- > > Hi Ingo, > > Kernel still crashes after applying the patch, > > CPU: Physical Processor ID: 0 > CPU: Processor Core ID: 0 > ACPI: Core revision 20080926 > Setting APIC routing to flat > BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 > IP: [] add_pin_to_irq_cpu+0x14/0x73 that is interesting, barrier() doesn't work, we do need that printk? YH -- 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/