On Wed, May 18, 2011 at 8:11 PM, Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote: > On 05/18/2011 08:04 AM, Mohammed Shafi wrote: >> >> On Wed, May 18, 2011 at 6:21 PM, Gertjan van Wingerde >> <gwingerde@xxxxxxxxx> wrote: >>> >>> On 05/18/11 14:41, Mohammed Shafi wrote: >>>> >>>> On Wed, May 18, 2011 at 5:26 PM, Walter Goldens >>>> <goldenstranger@xxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
