[Crash-utility] crash doesnt give complete backtrace

[Dave Anderson]

Adhiraj Joshi wrote:
> Hi All,
> 
> I get a kernel panic on my system and I see a long backtrace on the  
> console before the system freezes. I have kdump setup and analyse the 
> generated vmcore using crash. But the backtrace from crash is too short 
> and it doesnt give any relevant information. I wanted backtrace that 
> appeared on the console before freezing.
> 
> Any ideas on this?
> 
> Regards,
> Adhiraj.

When you say the system "freezes", but also that you get
a "kernel panic",  I'm not sure how the system entered the
kdump process, i.e., was panic() or BUG() called inside
the kernel, or did you enter sysrq-c?

Anyway, enter "log" to get the console log, where the final
trace should still exist.

In any case, depending upon how the system entered kdump,
the current context that was running may not be of
any interest.  Do a "bt -a" to see what's happening on the
other cpus at the time of the shutdown, or a "foreach bt"
to get the traces of all tasks.  If the current task *is*
the one you're interested in, but it still doesn't seem
"right", enter "bt -t" or "bt -T" to get a dump of all
text return addresses on the stack.

Dave