module debugging

[leo kirotawa]

IMO, I believe if you module is using/hanging all processors it's
impossible to kernel use any to print stuffs. What about try Sysrq [1]
?  I used it once in a power system plus xmon, but I'll be honest not
sure how it works on x86.

https://www.kernel.org/doc/Documentation/sysrq.txt

On Fri, Aug 21, 2015 at 8:06 AM, Salam Farhat <salalimo at gmail.com> wrote:
> Hi,
>
> I am not sure if this is the place to ask, if so please let me know where to
> do so.
>
> I am using a kernel module that I modified slightly to work on my current
> kernel version. It is running on a virtual machine and on a heavy load it
> goes into an infinite loop and freezes the system. I can tell that the
> virtual machine is using 100% of its assigned cpu. There are print
> statements almost everywhere in the module, but after a few seconds none get
> printed.
>
>
>
> The kernel has the following options already enabled:
> CONFIG_DETECT_SOFTLOCKUP  and
>
> CONFIG_DETECT_HUNG_TASK. To my understanding the kernel is supposed to print
> the stack trace when a hung task is detected, however, nothing gets printed
> in kern.log. I am not sure if this is the place where the kernel would dump
> the stack or if the print process is affected by the hang since the print
> statements in the module are not being printed as well.
>
>
>
> I would like to know how to debug this issue. Any help is appreciated.
>
>
>
> Thank you.
>
>
>
>
>
>
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-- 

----------------------------------------------
Leônidas S. Barbosa (Kirotawa)
blog: corecode.wordpress.com