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Message-ID: <86802c440807131134i351f967dh3a2b94d687c767ee@mail.gmail.com>
Date: Sun, 13 Jul 2008 11:34:04 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Vegard Nossum" <vegard.nossum@gmail.com>
Subject: Re: per-cpu related?
Cc: "Ingo Molnar" <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       "Mike Travis" <travis@sgi.com>, "Thomas Gleixner" <tglx@linutronix.de>,
       "Steven Rostedt" <rostedt@goodmis.org>
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On Sun, Jul 13, 2008 at 4:55 AM, Vegard Nossum <vegard.nossum@gmail.com> wrote:
> Hi,
>
> On Sun, Jul 13, 2008 at 10:16 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>> calling  pcie_portdrv_init+0x0/0x77
>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
>> IP: [<ffffffff802557de>] hrtick_start_fair+0x8e/0x178
>> PGD 0
>> Oops: 0000 [1] SMP
>> CPU 4
>> Modules linked in:
>> Pid: 103, comm: events/4 Not tainted 2.6.26-rc9-tip-01834-g99e624f-dirty #354
>> RIP: 0010:[<ffffffff802557de>]  [<ffffffff802557de>]
>> hrtick_start_fair+0x8e/0x178
>
> I find that this corresponds to timer->base being NULL:
>
> static inline int hrtimer_is_hres_active(struct hrtimer *timer)
> {
>        return timer->base->cpu_base->hres_active;
> }
>
> Apparently timer->base can legitimately be NULL in some cases:

thanks

could be caused by max_low_pfn_mapped patch...because hpet still use
fixmap address that is cleared by others.

will check that.

YH