linux-kernel - Re: [PATCH] irq: Guard handle_bad

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Message-ID: <d30c98fa-27eb-ff6d-cfc8-8fa4d95fc40c@roeck-us.net>
Date:   Sat, 2 Dec 2017 09:11:32 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Joe Perches <joe@...ches.com>, Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Dmitry Torokhov <dtor@...omium.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH] irq: Guard handle_bad_irq log messages

On 12/02/2017 08:52 AM, Joe Perches wrote:
> On Sat, 2017-12-02 at 08:29 -0800, Guenter Roeck wrote:
>> An interrupt storm on a bad interrupt will cause the kernel
>> log to be clogged.
>>
>> [   60.089234] ->handle_irq():  ffffffffbe2f803f,
>> [   60.090455] 0xffffffffbf2af380
>> [   60.090510] handle_bad_irq+0x0/0x2e5
>> [   60.090522] ->irq_data.chip(): ffffffffbf2af380,
>> [   60.090553]    IRQ_NOPROBE set
>> [   60.090584] ->handle_irq():  ffffffffbe2f803f,
>> [   60.090590] handle_bad_irq+0x0/0x2e5
>> [   60.090596] ->irq_data.chip(): ffffffffbf2af380,
>> [   60.090602] 0xffffffffbf2af380
>> [   60.090608] ->action():           (null)
>> [   60.090779] handle_bad_irq+0x0/0x2e5
>>
>> This was seen when running an upstream kernel on Acer Chromebook R11.
>> The system was unstable as result.
>>
>> Guard the log message with __printk_ratelimit to reduce the impact.
>> This won't prevent the interrupt storm from happening, but at least
>> the system remains stable.
> 
> Thanks.
> 
> There is also dummychip.c
> 
> Perhaps this should be updated in the
> static inline in kernel/irq/debug.h instead.
> 

Agreed, makes sense. I'll send an updated patch.

Guenter

>> diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
> []
>> @@ -28,9 +28,11 @@
>>    */
>>   void handle_bad_irq(struct irq_desc *desc)
>>   {
>> +	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);
>>   	unsigned int irq = irq_desc_get_irq(desc);
>>   
>> -	print_irq_desc(irq, desc);
>> +	if (__ratelimit(&ratelimit))
>> +		print_irq_desc(irq, desc);
>>   	kstat_incr_irqs_this_cpu(desc);
>>   	ack_bad_irq(irq);
>>   }
>