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SubjectRe: [REGRESSION] x86: support for new UV apic
Ingo Molnar wrote:
> * Priit Laes <plaes@plaes.org> wrote:
>
>> Hey,
>>
>> I am getting two following warnings (probable one per each CPU core)
>> using the latest Linus's git:
>>
>> WARNING: at arch/x86/kernel/genapic_64.c:86 read_apic_id+0x30/0x62()
>> Modules linked in:
>> Pid: 1, comm: swapper Not tainted 2.6.25-03563-gf7288b1 #20
>
> thanks - could you check the patch below, does it fix the warnings?

Hi Ingo ,

I got the same warning on my Core2Quad Q9300 box , your patch fixes the warning for me.


>
> Ingo
>
> --------------->
> Subject: x86: disable preemption in native_smp_prepare_cpus
> From: Ingo Molnar <mingo@elte.hu>
> Date: Fri Apr 18 11:07:10 CEST 2008
>
> Priit Laes reported the following warning:
>
> Call Trace:
> [<ffffffff8022f1e1>] warn_on_slowpath+0x51/0x63
> [<ffffffff80282e48>] sys_ioctl+0x2d/0x5d
> [<ffffffff805185ff>] _spin_lock+0xe/0x24
> [<ffffffff80227459>] task_rq_lock+0x3d/0x73
> [<ffffffff805133c3>] set_cpu_sibling_map+0x336/0x350
> [<ffffffff8021c1b8>] read_apic_id+0x30/0x62
> [<ffffffff806d921d>] verify_local_APIC+0x90/0x138
> [<ffffffff806d84b5>] native_smp_prepare_cpus+0x1f9/0x305
> [<ffffffff806ce7b1>] kernel_init+0x59/0x2d9
> [<ffffffff80518a26>] _spin_unlock_irq+0x11/0x2b
> [<ffffffff8020bf48>] child_rip+0xa/0x12
> [<ffffffff806ce758>] kernel_init+0x0/0x2d9
> [<ffffffff8020bf3e>] child_rip+0x0/0x12
>
> fix this by generally disabling preemption in native_smp_prepare_cpus().
>
> Reported-and-bisected-by: Priit Laes <plaes@plaes.org>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/kernel/smpboot.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> 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;
> @@ -1197,7 +1198,7 @@ void __init native_smp_prepare_cpus(unsi
> if (smp_sanity_check(max_cpus) < 0) {
> printk(KERN_INFO "SMP disabled\n");
> disable_smp();
> - return;
> + goto out;
> }
>
> preempt_disable();
> @@ -1237,6 +1238,8 @@ void __init native_smp_prepare_cpus(unsi
> printk(KERN_INFO "CPU%d: ", 0);
> print_cpu_info(&cpu_data(0));
> setup_boot_clock();
> +out:
> + preempt_enable();
> }
> /*
> * Early setup to make printk work.


Regards,

Gabriel


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