linux-kernel - Re: In many cases softlockup can not be reported after disabling IRQ for long time

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Message-ID: <CAOwKts_dTvc4LiCZUXN9oYzty1pkDEn_VQwPKY=EoVzk0n6tFA@mail.gmail.com>
Date:	Wed, 1 Feb 2012 10:18:09 +0800
From:	TAO HU <tghk48@...orola.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	linux-arm-kernel@...ts.infradead.org,
	linux-omap <linux-omap@...r.kernel.org>
Subject: Re: In many cases softlockup can not be reported after disabling IRQ
 for long time

Hi, Don

Thanks for your feedback!

Unfortunately, the hardlockup depends on NMI which is not available on
ARM (Cortex-A9) per my understanding.
Our system uses OMAP4430. Any more suggestions?

On Tue, Jan 31, 2012 at 11:47 PM, Don Zickus <dzickus@...hat.com> wrote:
> On Tue, Jan 31, 2012 at 03:28:09PM +0800, TAO HU wrote:
>> Resend with a new subject
>>
>> On Wed, Jan 25, 2012 at 4:24 PM, TAO HU <tghk48@...orola.com> wrote:
>> > Hi, All
>> >
>> > While playing kernel 3.0.8 with below test code, it does NOT report
>> > any softlockup with 60%~70% chances.
>> > NOTE: the softlockup timeout is set to 10 seconds (i.e.
>> > watchdog_thresh=5) in my test.
>> > ... ...
>> > preempt_disable();
>> > local_irq_disable();
>> > for (i = 0; i < 20; i++)
>> >       mdelay(1000);
>> > local_irq_enable();
>> > preempt_enable();
>> > ... ...
>> >
>> > However, if I remove local_irq_disable()/local_irq_enable() it will
>> > report softlockup with no problem.
>> > I believe it is due to that after local_irq_enable()
>> > touch_softlockup_watchdog() is called prior softlockup timer.
>
> Hi Hu,
>
> Honestly, you should be getting hardlockup warnings if you are disabling
> interrupts.  Do you see anything in the console output?
>
> Cheers,
> Don



-- 
Best Regards
Hu Tao
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