Re: 2.6.25-git2: BUG: unable to handle kernel paging request atffffffffffffffff

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> >  CPU: L2 cache: 4096K
> >  CPU: Physical Processor ID: 0
> >  CPU: Processor Core ID: 1
> >  x86: PAT support disabled.
> >  SPIN IRQ ALREADY DISABLED
> >  Pid: 0, comm: swapper Not tainted 2.6.25 #57
> > 
> >  Call Trace:
> >   [_spin_lock_irq+126/128] _spin_lock_irq+0x7e/0x80
> >   [lock_ipi_call_lock+16/32] lock_ipi_call_lock+0x10/0x20
> >  CPU1: Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz
> > [start_secondary+68/206] start_secondary+0x44/0xce
> 
> This is indeed an interesting issue: arch/x86/kernel/smpboot.c does an 
> IPI call to start_secondary, and yes, it looks suspicious to have that 
> lock_ipi_call_lock there (and in particular the unlock_ipi_call_lock 
> that enables interrupts within it). Ingo?

hm, irqs already disabled isnt bad in itself and it happens all the 
time. The irq enabling in unlock_ipi_call_lock() should be OK.

Any race with irqs there should at most result in a hung or crashed 
bootup, not in any memory corruption i believe.

	Ingo
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