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

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Message-ID: <20120821165006.GA24559@localhost>
Date:	Wed, 22 Aug 2012 00:50:06 +0800
From:	Fengguang Wu <fengguang.wu@...el.com>
To:	Michael Wang <wangyun@...ux.vnet.ibm.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 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,
Fengguang
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