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Date: Fri, 17 Aug 2012 10:00:46 +0800
From: Fengguang Wu <fengguang.wu@intel.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>, Oliver Neukum <oneukum@suse.de>,
        =?utf-8?B?QmrDuHJu?= Mork <bjorn@mork.no>,
        Sarah Sharp <sarah.a.sharp@linux.intel.com>,
        linux-kernel@vger.kernel.org,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "Lan, Tianyu" <tianyu.lan@intel.com>
Subject: Re: BUG: unable to handle kernel paging request in usb_match_id()
Message-ID: <20120817020046.GA24406@localhost>
References: <20120805025938.GA8954@localhost>
 <20120805165826.GB13913@kroah.com>
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On Sun, Aug 05, 2012 at 09:58:26AM -0700, Greg KH wrote:
> On Sun, Aug 05, 2012 at 10:59:38AM +0800, Fengguang Wu wrote:
> > Hi all,
> > 
> > This line triggers an oops in kvm boot test:
> > 
> > usb_match_id():
> > ==>      748         for (; id->idVendor || id->idProduct || id->bDeviceClass ||
> >          749                id->bInterfaceClass || id->driver_info; id++) {
> >          750                 if (usb_match_one_id(interface, id))
> >          751                         return id;
> >          752         }
> > 
> > It's an old bug and happens also in linux 3.0. It's very reproducible
> > for the attached config. I can send the initrd (yocto-minimal-i386.cgz)
> > on your request in private email.
> 
> Odds are a driver without a terminating NULL for the device id list is
> causing this to fail.
> 
> What devices are in the system and what drivers are trying to be bound?

The last match is for: drivers/usb/misc/emi62.c

Located down by Tianyu's debug patch:

[    2.206708] usb_device_match: device 1-1:1.0, driver cytherm
[    2.207627] usb_device_match: device 1-1:1.0, driver emi62 - firmware loader
[    2.208769] BUG: unable to handle kernel paging request at c1f7478e
[    2.209726] IP: [<c14ac1c0>] usb_match_id+0x5b/0xcd

> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -778,7 +778,8 @@ static int usb_device_match(struct device *dev, struct device_driver *drv)
>
>                 intf = to_usb_interface(dev);
>                 usb_drv = to_usb_driver(drv);
> -
> +
> +               pr_info("%s: device %s, driver %s \n", dev_name(dev), drv->name);
>                 id = usb_match_id(intf, usb_drv->id_table);
>                 if (id)
>                         return 1;

Thanks,
Fengguang
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