2.6.31-rc5-git2 crash on a idle system.

Sachin Sant sachinp at in.ibm.com
Thu Aug 6 23:33:37 EST 2009

Benjamin Herrenschmidt wrote:
> Thanks. Since it's a memory corruption (or seems to be) however, it's
> possible that the bisection will mislead you. IE. The culprit could be
> somewhere else, and the commit you'll find via bisection just happens to
> move things around in the kernel in such a way that the corruption hits
> that code path instead of another rarely used one.
> I would suggest using printk to print out the content of memory where
> the code appears to have been smashed at different stages during boot
> (maybe even in the initcalls loop in init/main.c) to try to point out
> what appears to be causing the corruption.
By the time machine is up and running the particular memory location
in question is already overwritten. So seems like the corruption occurs
during the boot.

I added few printks in the initcall debug code patch. The o/p suggests
that by the time first initicall debug message is printed the code is
already corrupted. Further debug suggests, when start_kernel() is
called the code at address(0xc000000000600000) is already corrupted.
About 28 bytes of code starting from the above address is overwritten. 

I will try to add few more debug statements to find the place where
this corruption might me happening.



Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India

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