From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933608AbWKQN1p (ORCPT ); Fri, 17 Nov 2006 08:27:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933607AbWKQN1p (ORCPT ); Fri, 17 Nov 2006 08:27:45 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:9704 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S933608AbWKQN1n (ORCPT ); Fri, 17 Nov 2006 08:27:43 -0500 Date: Fri, 17 Nov 2006 14:26:18 +0100 From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Wolfgang Erig , Andreas Friedrich , Adrian Bunk , Greg Kroah-Hartman , Linus Torvalds Subject: [patch] i386/x86_64: ACPI cpu_idle_wait() fix Message-ID: <20061117132618.GA14411@elte.hu> References: <20061116110558.GB14245@elte.hu> <20061116122820.GA2718@upset.pdb.fsc.net> <20061116123335.GA1392@elte.hu> <20061116124132.GA9048@upset.pdb.fsc.net> <20061116131842.GA12961@elte.hu> <20061116133019.GA14546@upset.pdb.fsc.net> <20061116144356.GA4891@elte.hu> <20061117090356.GA26013@upset.pdb.fsc.net> <20061117112237.GA26270@elte.hu> <20061117124913.GA24893@upset.pdb.fsc.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061117124913.GA24893@upset.pdb.fsc.net> User-Agent: Mutt/1.4.2.2i X-ELTE-SpamScore: -3.7 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.7 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_40 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -1.1 BAYES_40 BODY: Bayesian spam probability is 20 to 40% [score: 0.2424] 0.7 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Subject: [patch] i386/x86_64: ACPI cpu_idle_wait() fix From: Ingo Molnar The scheduler on Andreas Friedrich's hyperthreading system stopped working properly as of 2.6.18: the scheduler would never move tasks to another CPU! after a couple of attempts to corner the bug, the following smoking gun was found: BIOS reported wrong ACPI idfor the processor CPU#1: set_cpus_allowed(), swapper:1, 3 -> 2 [] show_trace_log_lvl+0x34/0x4a [] show_trace+0x2c/0x2e [] dump_stack+0x2b/0x2d [] set_cpus_allowed+0x52/0xec [] cpu_idle_wait+0x2e/0x100 [] acpi_processor_power_exit+0x45/0x58 [] acpi_processor_remove+0x46/0xea [] acpi_start_single_object+0x47/0x54 [] acpi_bus_register_driver+0xa4/0xd3 [] acpi_processor_init+0x57/0x77 [] init+0x146/0x2fd [] kernel_thread_helper+0x7/0x10 a quick look at cpu_idle_wait() shows how broken that code is on i386: it changes the init task's affinity map but never restores it ... and because all userspace tasks get forked by init, they all inherited that single-CPU affinity mask. x86_64 cloned this bug too. Signed-off-by: Ingo Molnar --- arch/i386/kernel/process.c | 4 +++- arch/x86_64/kernel/process.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-) Index: linux/arch/i386/kernel/process.c =================================================================== --- linux.orig/arch/i386/kernel/process.c +++ linux/arch/i386/kernel/process.c @@ -205,7 +205,7 @@ void cpu_idle(void) void cpu_idle_wait(void) { unsigned int cpu, this_cpu = get_cpu(); - cpumask_t map; + cpumask_t map, tmp = current->cpus_allowed; set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); put_cpu(); @@ -227,6 +227,8 @@ void cpu_idle_wait(void) } cpus_and(map, map, cpu_online_map); } while (!cpus_empty(map)); + + set_cpus_allowed(current, tmp); } EXPORT_SYMBOL_GPL(cpu_idle_wait); Index: linux/arch/x86_64/kernel/process.c =================================================================== --- linux.orig/arch/x86_64/kernel/process.c +++ linux/arch/x86_64/kernel/process.c @@ -144,7 +144,7 @@ static void poll_idle (void) void cpu_idle_wait(void) { unsigned int cpu, this_cpu = get_cpu(); - cpumask_t map; + cpumask_t map, tmp = current->cpus_allowed; set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); put_cpu(); @@ -167,6 +167,8 @@ void cpu_idle_wait(void) } cpus_and(map, map, cpu_online_map); } while (!cpus_empty(map)); + + set_cpus_allowed(current, tmp); } EXPORT_SYMBOL_GPL(cpu_idle_wait);