Subject: Re: [PATCH] x86: check for valid irq_cfg pointer in
 smp_irq_move_cleanup_interrupt
From: Suresh Siddha <suresh.b.siddha@intel.com>
Reply-To: Suresh Siddha <suresh.b.siddha@intel.com>
To: Dimitri Sivanich <sivanich@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Yinghai Lu <yinghai@kernel.org>,
        Naga Chumbalkar <nagananda.chumbalkar@hp.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        linux-kernel@vger.kernel.org
Date: Mon, 21 May 2012 14:10:39 -0700
In-Reply-To: <20120521210901.GA25326@sgi.com>
References: <20120521164959.GE16454@sgi.com>
	 <1337634353.1997.144.camel@sbsiddha-desk.sc.intel.com>
	 <20120521210901.GA25326@sgi.com>
Organization: Intel Corp
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On Mon, 2012-05-21 at 16:09 -0500, Dimitri Sivanich wrote:
> On Mon, May 21, 2012 at 02:05:53PM -0700, Suresh Siddha wrote:
> > On Mon, 2012-05-21 at 11:49 -0500, Dimitri Sivanich wrote:
> > > The smp_irq_move_cleanup_interrupt routine should be checking for a valid
> > > irq_cfg pointer prior to accessing it.  It also seems that this should be
> > > done after taking the desc lock.
> > 
> > I think these changes are correct. Did you see any crashes during module
> > unload etc?
> 
> Yes, we have seen these on occasion during boot.

During boot or shutdown?

Review of the code shows that this can trigger during module unload
which can call destroy_irq() etc and can trigger the crash if there is a
parallel irq migration related cleanup.

Unsuccessful module loads can also call destroy_irq() but I doubt that
is what happening here.

thanks,
suresh


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