From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 18 Apr 2008 11:22:55 +0200 From: Ingo Molnar Subject: Re: 2.6.25-mm1: not looking good Message-ID: <20080418092254.GA20661@elte.hu> References: <20080417160331.b4729f0c.akpm@linux-foundation.org> <20080418005034.6e4dd9e7.akpm@linux-foundation.org> <20080418005323.7c015c42.akpm@linux-foundation.org> <20080418005733.aa3e8250.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080418005733.aa3e8250.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Thomas Gleixner , Pekka Enberg , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, James Morris , Stephen Smalley , Peter Zijlstra , linux-pm@lists.linux-foundation.org, Greg KH , "Rafael J. Wysocki" , Pavel Machek , Jack Steiner , Mike Travis , Alan Mayer List-ID: * Andrew Morton wrote: > WARNING: at arch/x86/kernel/genapic_64.c:86 read_apic_id+0x31/0x67() > > [] ? debug_smp_processor_id+0x32/0xc4 > [] read_apic_id+0x31/0x67 > [] verify_local_APIC+0xa7/0x163 > [] native_smp_prepare_cpus+0x1ed/0x301 > [] kernel_init+0x5a/0x276 that came in via the UV-APIC patchset but the warning is entirely harmless. At that point we've got a single CPU running only so preemption of that code to another CPU is not possible. native_smp_prepare_cpus() should probably just disable preemption, that way we could remove all those ugly preempt disable-enable calls from the called functions - per the patch below. (not boot tested yet - might provoke atomic-scheduling warnings if i forgot about some schedule point in this rather large codepath) Ingo -------------------> Subject: x86: disable preemption in native_smp_prepare_cpus From: Ingo Molnar Date: Fri Apr 18 11:07:10 CEST 2008 Signed-off-by: Ingo Molnar --- arch/x86/kernel/smpboot.c | 2 ++ 1 file changed, 2 insertions(+) Index: linux-x86.q/arch/x86/kernel/smpboot.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/smpboot.c +++ linux-x86.q/arch/x86/kernel/smpboot.c @@ -1181,6 +1181,7 @@ static void __init smp_cpu_index_default */ void __init native_smp_prepare_cpus(unsigned int max_cpus) { + preempt_disable(); nmi_watchdog_default(); smp_cpu_index_default(); current_cpu_data = boot_cpu_data; @@ -1237,6 +1238,7 @@ void __init native_smp_prepare_cpus(unsi printk(KERN_INFO "CPU%d: ", 0); print_cpu_info(&cpu_data(0)); setup_boot_clock(); + preempt_enable(); } /* * Early setup to make printk work. -- 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