Ubuntu

How to solve kernel panic when Wifi adapter is plugged in?

Asked by Bernhard G

Hi,

since updating my Lubuntu 16.10 system (linux-image-4.8.0-37-generic to linux-image-4.8.0-38-generic) the kernel panics as soon as I plug in the Wifi Adapter (Edimax EW-7612UAn Wifi USB Adapter).
The coredump logs
BUG: unable to handle kernel NULL pointer dereference @0000000000000048
IP: [<ffffffffc0786647>] rtl_lps_leave+0x17/0x50 [rtlwifi]
PGD 0
Ooops: 0000 [#1] SMP
This is followed by the Modules linked in, Hardware info, Stack trace.
At the end of the trace it says:
Kernel panic - not syncing: Fatal exception in interrupt.

I uploaded a console screenshot to my google drive: https://goo.gl/medcXj
and I didn't find anything suspicious in syslog or kernel log, most probably because the kernel panics almost instantly after plugging the usb adapter in.

Updating to linux-image-4.8.0-39-generic does not solve the issue as well.

Could you please advise how to continue?

Thank you!

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Manfred Hampl (m-hampl) said : 		#1

Does the adapter work if you boot the older 4.8.0-37-generic kernel (by selecting advanced options in the grub menu)?

Remarks:
1. there was a change in the rtlwifi module for 4.8.0-38 "rtlwifi: Fix enter/exit power_save", see Bug #1655057
2. there is bug report Bug #1666615 looking quite similar, but referring to kernel 4.4.0-63-generic

You might consider creating a bug report about your crash, see also https://help.ubuntu.com/community/ReportingBugs

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actionparsnip (andrew-woodhead666) said : 		#2

Have you tried a different USB port?

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Bernhard G (bernhard001-gmx) said : 		#3

Manfred Hampl:
> Does the adapter work if you boot the older 4.8.0-37 kernel?
 Yes, it does.

actionparsnip:
> Have you tried a different USB port?
 The first time I experienced it, I used a USB Port on the back panel of the computer. Then, for my experiments, I switched to the front panel.

Initially I was on my way to file a bug for this behavior, but there it says, that It might be a good idea to ask a question before, which is, what I then did.

Unrelated:
I don't know what is considered good behavior here. Should I mark this as "Problem solved" even though the original problem remains, but cannot be solved here?

Can you help with this problem?

Provide an answer of your own, or ask Bernhard G for more information if necessary.

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