Re: rt2x00: rt2800usb causing kernel panic /compat-wireless/

[Mohammed Shafi <shafi.wireless@gmail.com>]

On Wed, May 18, 2011 at 9:18 PM, Mohammed Shafi
<shafi.wireless@gmail.com> wrote:
> On Wed, May 18, 2011 at 9:15 PM, Mohammed Shafi
> <shafi.wireless@gmail.com> wrote:
>> just a quick update, once again I blindly used this patches which
>> seems to solve the problem,
>> agg-rx.c still uses the call_rcu thing, so I thought work.c ,
>> aggr-tx.c can make use of call_rcu .
>> thanks to the guy who mailed this patch!
>>
>> need to test more
>
> from this thread
> http://comments.gmane.org/gmane.linux.kernel.wireless.general/69332
>
> will test with compat wireless 16-05-2011

looks like reverting back to call_free_rcu fixes(with the help of the
compat-wireless-no-kfree-rcu.patch
) fixes this, thanks to Felix who pointed this backporting of kfree_rcu thing

>>
>>
>> On Wed, May 18, 2011 at 8:16 PM, Mohammed Shafi
>> <shafi.wireless@gmail.com> wrote:
>>> On Wed, May 18, 2011 at 8:11 PM, Larry Finger <Larry.Finger@lwfinger.net> wrote:
>>>> On 05/18/2011 08:04 AM, Mohammed Shafi wrote:
>>>>>
>>>>> On Wed, May 18, 2011 at 6:21 PM, Gertjan van Wingerde
>>>>> <gwingerde@gmail.com>  wrote:
>>>>>>
>>>>>> On 05/18/11 14:41, Mohammed Shafi wrote:
>>>>>>>
>>>>>>> On Wed, May 18, 2011 at 5:26 PM, Walter Goldens
>>>>>>> <goldenstranger@yahoo.com>  wrote:
>>>>>>>>>>
>>>>>>>>>> A very peculiar bug.
>>>>>>>>>>
>>>>>>>>>> With compat-wireless from 16.05 a nasty bug started to
>>>>>>>>>
>>>>>>>>> manifest itself. Right around association time, the
>>>>>>>>> rt2800usb causes kernel panic. The system freezes and the
>>>>>>>>> Caps Lock and Num Lock leds on the keyboard begin to flash.
>>>>>>>>>
>>>>>>>>> also ath9k, iwlagn.
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Unfortunately there are no recoverable traces after
>>>>>>>>>
>>>>>>>>> the system failure to aid this bug report or to indicate its
>>>>>>>>> origin.
>>>>>>>>>>
>>>>>>>>>> I believe it may somehow be related to Ubuntu's
>>>>>>>>>
>>>>>>>>> network-manager. If I turn off the network-manager service,
>>>>>>>>> I can go into monitor mode for example, but if
>>>>>>>>> network-manager is running and I plug my USB dongle, it
>>>>>>>>> starts to associate, a second or two later the system is in
>>>>>>>>> complete meltdown.
>>>>>>>>>
>>>>>>>>> same thing, monitor mode worked perfectly fine.
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Nothing concrete, but a hunch is telling me this has
>>>>>>>>>
>>>>>>>>> something to do with the association mechanism of the
>>>>>>>>> rt2800usb. Compat-wireless from few days back exhibits no
>>>>>>>>> such foul play.
>>>>>>>>>
>>>>>>>>> yes just right at the association complete freeze.
>>>>>>>>>
>>>>>>>>
>>>>>>>> That's strange. I wonder what's the connection with this bug and
>>>>>>>> network-manager. Because when I manually tried to associate, dmesg reported
>>>>>>>> the association attempt timed out.
>>>>>>>
>>>>>>> no even when we use iw dev connect command we can see the panic.
>>>>>>
>>>>>> Yeah, I've seen this freeze as well using one of the later
>>>>>> compat-wireless packages using just iw and wpa_supplicant to bring up the
>>>>>> card. This is on all sorts of rt2x00 supported devices.
>>>>>>
>>>>>> However, I don't believe this to be an rt2x00-specific bug, as exactly
>>>>>> the same rt2x00 sources inside a compat-wireless-2.6.39rc7 package do not
>>>>>> produce the freeze.
>>>>>>
>>>>>>> some expert suspected that there is a chance of kfree_rcu in
>>>>>>> compat-wireless may have caused the problem
>>>>>>>
>>>>>>
>>>>>> That's where my suspicion is as well, but I didn't have the time to
>>>>>> further investigate. Since my focus was on rt2x00 I used the
>>>>>> compat-wireless-2.6.39rc7 package to test my patches. I only did a quick
>>>>>> check, and the kfree_rcu compatibility fix that was done in compat-wireless
>>>>>> did seem to match the kfree_rcu code is present in linux-next, but maybe
>>>>>> there is an odd side-effect.
>>>>>
>>>>> I could not exactly remember this panic came just after kfree_rcu
>>>>> backported..
>>>>
>>>> This problem also occurs with rtl8192se from compat-wireless. When it was
>>>> reported to me, a photo of the console log was included (attached). The
>>>> crash is a NULL pointer in rcu_do_batch.clone.19 (I think - the photo
>>>> quality is minimal.).
>>>
>>> thanks!, same type of call trace which I had also obtained, hopefully there in
>>>  http://pastebin.com/CZrSZrme
>>>  http://pastebin.com/gwZJGDG4
>>>
>>>
>>>
>>>>
>>>> Larry
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> shafi
>>>
>>
>>
>>
>> --
>> shafi
>>
>
>
>
> --
> shafi
>



-- 
shafi