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SubjectRe: [REGRESSION] x86: support for new UV apic

* 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?

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.

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