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Subject: Re: crash by cdc_acm driver in kernels 4.8-rc1/5
To: wim@djo.tudelft.nl, Oliver Neukum <oneukum@suse.com>
References: <20160908115803.GA28274@djo.tudelft.nl>
 <1473337238.32073.2.camel@suse.com> <20160908125850.GC28274@djo.tudelft.nl>
 <1476713445.3938.1.camel@suse.com> <20161017152042.GA26559@djo.tudelft.nl>
 <1476793123.2637.3.camel@suse.com> <20161115001619.GA21030@djo.tudelft.nl>
Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
From: poma <pomidorabelisima@gmail.com>
Message-ID: <cdba9e09-6550-a4b5-a3ed-86ce212d8a4a@gmail.com>
Date: Tue, 15 Nov 2016 12:26:00 +0100
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On 15.11.2016 01:16, Wim Osterholt wrote:
> On Tue, Oct 18, 2016 at 02:18:43PM +0200, Oliver Neukum wrote:
> 
>> It definitely does not crash and is probed and your .config is not
>> extremely unusual.
> 
> Hmmm.
> 
>> ... Something odd is going on.
> 
> Whell, yes.
> The only thing that appears you'll have to do is unset 'CONFIG_SMP'.
> 
> My machines didn't have the luxury of multicore processors (until recently),
> so there never has been any reason to deliberately switch these options on!
> 
> In the process of searching, many options may have changed. The crash/OOPS
> has now mitigated into just a WARNING with a call trace.
> (Or it could be a totally different bug?)
> After the call trace the device is working normally and a shutdown
> completes to the end now.
> That is with the config given here:
> http://webserver.djo.tudelft.nl/.config-4.9-rc4.OK (CONFIG_SMP=y)
> http://webserver.djo.tudelft.nl/WARNING-4.9-rc4    (call trace for C_S unset)
> 
> Tests on other machines with (slightly) different configs all seem to
> confirm that the problems are gone when CONFIG_SMP is set.
> 
> Regards, Wim.
> 
> 

Try retest with mainline 4.9-rc5,
CONFIG_SMP was not crucial[1].

$ grep CONFIG_SMP /boot/config-4.9.0-0.rc5.git0.1.fc26.x86_64*
/boot/config-4.9.0-0.rc5.git0.1.fc26.x86_64:CONFIG_SMP=y
/boot/config-4.9.0-0.rc5.git0.1.fc26.x86_64+debug:CONFIG_SMP=y

[1] https://www.spinics.net/lists/linux-usb/msg148852.html