Hi,

I observed about the same message but after the line
Brought up 2 CPUs in dmesg.
However the system keeps running fine. 
I run a Core2 Duo processor.
dmesg dump is attached. 

------------[ cut here ]------------
WARNING: at kernel/lockdep.c:2662 check_flags+0x18d/0x190()
Modules linked in:
Pid: 0, comm: swapper Not tainted 2.6.25 #2

Call Trace:
 [<ffffffff8022fbff>] warn_on_slowpath+0x5f/0x80
 [<ffffffff80213a77>] ? native_sched_clock+0x57/0x80
 [<ffffffff8022ac1a>] ? hrtick_set+0x3a/0x120
 [<ffffffff80254da5>] ? __lock_acquire+0x245/0x1070
 [<ffffffff8022ac9d>] ? hrtick_set+0xbd/0x120
 [<ffffffff80213a77>] ? native_sched_clock+0x57/0x80
 [<ffffffff8024b0b0>] ? __atomic_notifier_call_chain+0x0/0xa0
 [<ffffffff8025180d>] check_flags+0x18d/0x190
 [<ffffffff80255c33>] lock_acquire+0x63/0xd0
 [<ffffffff8024b101>] __atomic_notifier_call_chain+0x51/0xa0
 [<ffffffff8020b210>] ? mwait_idle+0x0/0x50
 [<ffffffff8020b0a0>] ? default_idle+0x0/0x80
 [<ffffffff8024b161>] atomic_notifier_call_chain+0x11/0x20
 [<ffffffff8020a849>] __exit_idle+0x29/0x30
 [<ffffffff8020b178>] cpu_idle+0x58/0xa0
 [<ffffffff80450b5e>] start_secondary+0x2fe/0x430

---[ end trace ca143223eefdc828 ]---
possible reason: unannotated irqs-on.
irq event stamp: 12


Bernard Pidoux