linux-kernel - Re: BUG: scheduling while atomic, under native_smp_prepare

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Message-ID: <50343EF1.5060008@linux.vnet.ibm.com>
Date:	Wed, 22 Aug 2012 10:07:45 +0800
From:	Michael Wang <wangyun@...ux.vnet.ibm.com>
To:	Fengguang Wu <fengguang.wu@...el.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Yinghai Lu <yinghai@...nel.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: BUG: scheduling while atomic, under native_smp_prepare_cpus()

On 08/22/2012 12:50 AM, Fengguang Wu wrote:
> On Mon, Aug 20, 2012 at 05:42:22PM +0800, Michael Wang wrote:
>> On 08/20/2012 05:27 PM, Fengguang Wu wrote:
>>> Hi Michael,
>>>
>>> On Mon, Aug 20, 2012 at 05:20:35PM +0800, Michael Wang wrote:
>>>> On 08/17/2012 09:49 PM, Fengguang Wu wrote:
>>>>
>>>> Hi, FengGuang
>>>>
>>>> native_smp_prepare_cpus has already disabled the preempt before
>>>> reach __irq_alloc_descs(), and sleep in mutex_lock() cause the bug.
>>>>
>>>> May be the follow patch could help to solve the issue(actually I
>>>> think the true problem should be in _cond_resched...).
>>>
>>> Is this a debug patch? Since what it does is to conditionally disable
>>> the warning.
>>
>> No, I use this as a solution, it should work as the bug reported in boot
>> process before init_post called.
>>
>> We have some reference from __might_sleep which also avoid the check if
>> system has not fully booted, so I think this way is acceptable, but I'm
>> not the one to make decision...
> 
> Fair enough.
> 
>>>
>>>> I can't do test by my self since I can't reproduce the issue on my
>>>> machine, the kernel_init thread never got a need sched flag set at
>>>> that moment in my case...
>>>
>>> I'll try it and report back :)
>>
>> Appreciate :)
> 
> It works! :)
> 
> Tested-by: Fengguang Wu <wfg@...ux.intel.com>

Thanks for your testing, I will send out the patch later with your
Tested-by :)

Regards,
Michael Wang

> 
> Thanks,
> Fengguang
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