how to avoid CPU watchdog error during debug

how to avoid CPU watchdog error during debug

[ckim]

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Hello,

While debugging a kernel module, I get this error and the OS crashes.

[39068.833652] rcu: INFO: rcu_sched self-detected stall on CPU

[39068.834739] watchdog: BUG: soft lockup - CPU#3 stuck for 164s!
[systemd-journal:399]

[39068.834854] watchdog: BUG: soft lockup - CPU#0 stuck for 164s!
[test_axpu_app:2896]

This seems because I stopped the processor for debugging.

How can I avoid this watchdog error during debug?

Any help will be appreciated. Thanks!

 

Chan Kim


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Re: how to avoid CPU watchdog error during debug

[Philipp Hortmann]

On 8/25/21 3:06 AM, ckim@etri.re.kr wrote:
> Hello,
> 
> While debugging a kernel module, I get this error and the OS crashes.
> 
> [39068.833652] rcu: INFO: rcu_sched self-detected stall on CPU
> 
> [39068.834739] watchdog: BUG: soft lockup - CPU#3 stuck for 164s! 
> [systemd-journal:399]
> 
> [39068.834854] watchdog: BUG: soft lockup - CPU#0 stuck for 164s! 
> [test_axpu_app:2896]
> 
> This seems because I stopped the processor for debugging.
> 
> How can I avoid this watchdog error during debug?
> 
> Any help will be appreciated. Thanks!
> 
> Chan Kim
> 
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> 

Hi Kim,

since many things are time depending in the kernel it is difficult to 
stop parts of the kernel. The question is if it is really absolutely 
necessary to do this? Why you can not do it by logging with printk?

Debugging is described in:
https://www.doc-developpement-durable.org/file/Projets-informatiques/cours-&-manuels-informatiques/Linux/Linux%20Kernel%20Development,%203rd%20Edition.pdf

See Chapter 18 Debugging

Thanks! Bye Philipp







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RE: how to avoid CPU watchdog error during debug

[ckim]

> 
> since many things are time depending in the kernel it is difficult to stop
> parts of the kernel. The question is if it is really absolutely necessary
> to do this? Why you can not do it by logging with printk?
> 
> Debugging is described in:
> https://www.doc-developpement-durable.org/file/Projets-
> informatiques/cours-&-manuels-
> informatiques/Linux/Linux%20Kernel%20Development,%203rd%20Edition.pdf
> 
> See Chapter 18 Debugging
> 
> Thanks! Bye Philipp
> 
Hi, Philipp,
I've found your answer too late. Thanks for the info(I learned something
about the early_prink from the book). 
Actually, shortly after I sent my question, I learned how to make printk
appear in the console (not in the dmesg buffer) and was using it.
(I added the line "kernel.prink = 5 4 1 7" in the /etc/sysctl.conf file.  
So I've set the default console log level to 5 making default printk appear
in the console.)
Thanks!

Chan
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies





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Re: how to avoid CPU watchdog error during debug

[jim.cromie]

On Sun, Aug 29, 2021 at 7:46 PM <ckim@etri.re.kr> wrote:
>
>
> >
> > since many things are time depending in the kernel it is difficult to stop
> > parts of the kernel. The question is if it is really absolutely necessary
> > to do this? Why you can not do it by logging with printk?
> >
> > Debugging is described in:
> > https://www.doc-developpement-durable.org/file/Projets-
> > informatiques/cours-&-manuels-
> > informatiques/Linux/Linux%20Kernel%20Development,%203rd%20Edition.pdf
> >
> > See Chapter 18 Debugging
> >
> > Thanks! Bye Philipp
> >
> Hi, Philipp,
> I've found your answer too late. Thanks for the info(I learned something
> about the early_prink from the book).
> Actually, shortly after I sent my question, I learned how to make printk
> appear in the console (not in the dmesg buffer) and was using it.
> (I added the line "kernel.prink = 5 4 1 7" in the /etc/sysctl.conf file.
> So I've set the default console log level to 5 making default printk appear
> in the console.)
> Thanks!
>
> Chan


thanks for the followup

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