x86: disable preemption in native_smp_prepare_cpus
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>
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3898849..56078d6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1190,6 +1190,7 @@
*/
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;
@@ -1206,7 +1207,7 @@
if (smp_sanity_check(max_cpus) < 0) {
printk(KERN_INFO "SMP disabled\n");
disable_smp();
- return;
+ goto out;
}
preempt_disable();
@@ -1246,6 +1247,8 @@
printk(KERN_INFO "CPU%d: ", 0);
print_cpu_info(&cpu_data(0));
setup_boot_clock();
+out:
+ preempt_enable();
}
/*
* Early setup to make printk work.