callgraph-0.2.diff patch with newer 2.6 kernels

[Will C. <wc...@re...>]

I tried the callgraph-0.2.diff patch with the relatively recent kernel 
2.6.4 kernel (kernel-source-2.6.4-1.275 from 
http://people.redhat.com/arjanv/2.6/). The patch appears to work with 
earlier version of the kernel, linux-2.6.2-1.180. However, with this 
2.6.4 kernel the call graph code causes the machine to lock up. Used the 
following to start oprofile.

$ sudo /usr/local/bin/opcontrol --setup 
--vmlinux=/home/wcohen/oprofile/linux-2.6.4-1.275.callgraph/vmlinux 
--separate=library --callgraph=2
$ sudo /usr/local/bin/opcontrol --start --callgraph=2


I have done some exploring using "#ifdef 0" and "#endif" to exclude 
certain sections of code. The problem seems to be in the backtrace.c for 
the user space code. The kernel backtrace in backtrace.c:x86_backtrace() 
seems to work fine. However, the corresponding loop later in 
x86_backtrace() for the userspace backtrace hangs. I made a copy of 
dump_backtrace for the userspace loop then made the new function return 
immediately rather than recording the return address. This avoided lock up.

Anyone else noticed similar problems?

-Will