Message-ID: <5195242A.4040007@oracle.com>
Date: Thu, 16 May 2013 14:23:38 -0400
From: Sasha Levin <sasha.levin@oracle.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130429 Thunderbird/17.0.5
MIME-Version: 1.0
To: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>
CC: "Liu, Chuansheng" <chuansheng.liu@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Wu, Fengguang" <fengguang.wu@intel.com>,
        "eag0628@gmail.com" <eag0628@gmail.com>, Dave Jones <davej@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        John Stultz <johnstul@us.ibm.com>
Subject: Re: WARNING: at kernel/smp.c:385 smp_call_function_many
References: <5170602E.3050206@oracle.com> <27240C0AC20F114CBF8149A2696CBE4AC1B56C@SHSMSX101.ccr.corp.intel.com> <51708FE5.6000301@oracle.com>
In-Reply-To: <51708FE5.6000301@oracle.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1621
Lines: 41

On 04/18/2013 08:29 PM, Sasha Levin wrote:
> Hi Liu,
> 
> On 04/18/2013 08:10 PM, Liu, Chuansheng wrote:
>>> It seems that with commit "smp: Give WARN()ing when calling
>>>> smp_call_function_many()/single() in serving irq" I'm getting a bunch of these:
>> This patch gives the warning even when the smp_call_function_many() is called in softirq context,
>> because it will bring the possible deadlock cases, the example is below:
>> CPUA                            CPUB
>>                                 spin_lock(&spinlock)
>>                                 Any irq coming, call the irq handler
>>                                 irq_exit()
>> spin_lock_irq(&spinlock)
>> <== Blocking here due to
>> CPUB hold it
>>                                   __do_softirq()
>>                                     run_timer_softirq()
>>                                       timer_cb()
>>                                         call smp_call_function_many()
>>                                           send IPI interrupt to CPUA
>>                                             wait_csd()
>>
>> Then both CPUA and CPUB will be deadlocked here.
> 
> Right.
> 
> So commit f55a6faa3 ("hrtimer: Provide clock_was_set_delayed()") followed by one
> of the commits that used clock_was_set_delayed() may trigger the deadlock you've
> described. (cc John Stultz...)

Ping?


Thanks,
Sasha

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/