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Subject: Re: Kernel Oops: btusb: 4.2rc1 System lockup with BT dongle insert -
 log attached
To: simon@mungewell.org, "Kim, Milo" <milo.kim@ti.com>
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Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org
From: Laura Abbott <labbott@redhat.com>
Message-ID: <55A93A10.3060201@redhat.com>
Date: Fri, 17 Jul 2015 10:23:28 -0700
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On 07/17/2015 08:14 AM, simon@mungewell.org wrote:
>
>>> So in summary this problem is showing up now as the 'User Helper
>>> Fallback'
>>> is now forced on, obviously the underlying problem needs to be fixed -
>>> but
>>> I don't know when it crept in.
>>>
>>
>> The 'CONFIG_FW_LOADER_USER_HELPER_FALLBACK' enables to load firmware
>> data manually by accessing /sys/class/firmware/<name>/data. It runs in
>> case the firmware file is missing.
>> This user helper fallback will be enabled if one of LP55xx driver is
>> included in your dot config. Please see my patch below.
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/leds?id=b67893206fc0a0e8af87130e67f3d8ae553fc87c
>>
>> However, I'm not sure why this affects your system lockup. Can I have
>> more details?
>
> Hi Milo,
> I'm not suggesting that your patch is the cause, just that it is an
> 'enabler' and and explains why the problem (system lockup when I plug USB
> Bluetooth dongle in) appears now.
>
> A full Oops log is further back in this thread:
> http://www.spinics.net/lists/linux-bluetooth/msg63090.html
>
>
>>> Will try building 4.1 with this option to see if it fails.
>
> A very quick test as I was leaving the house this morning shows that 4.1
> with 'CONFIG_FW_LOADER_USER_HELPER_FALLBACK' does not show the problem.
>
> So at least we know the 'real' problem is a recent change to the code.
> Simon
>

I think this was reported and fixed

https://lkml.org/lkml/2015/7/8/858
https://lkml.org/lkml/2015/7/8/1199
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6f957724b94cb19f5c1c97efd01dd4df8ced323c

Thanks,
Laura