Originally posted by: SystemAdmin

Hello all,

One of the application we port to Aix from linux Segmentation faults when it exits. Here is part of backtrace of SEGV:
(dbx) where
splay(??, ??, ??) at
free_y(??, ??) at
free_common(??) at
....
exit(??) at
...

Application seem to perform everything expected well and while exiting it SEGV. By doing lot of googling learnt this could be due to hash corruption.

Tried the following:
1. setenv MALLOCDEBUG verbose

Result:
Malloc Report: The address passed to free, <x>, is
outside the valid range of addresses allocated by malloc (errno = 2).

2. setenv MALLOCTYPE debug
Run the application no SEGV at all. It exits normally.

3. setenv MALLOCTYPE watson
setenv MALLOCDEBUG catch_overflow

Run the application no SEGV at all. It exits normally.

Tried running same application same way with valgrind, totalview, MEMORY_CHECK_2 in linux to find potential coding error but found none.

Queries:
1. How can I find what is happening in memory address "x"? Who changes/disturbs it? Tried setting a watchpoint for that location but the error was:
Unreadable instruction at address 0x10000000
What else can i do? How can I find what happens in this location?

2. What difference does malloctype debug/watson does compared to default(yoktown)? Why isn't there a SEGV at that time?

3. Is there any tool to watch/examine heap?

4. Is there any other tool/option which could be used to debug this problem further?

Any pointers/suggestions/help is most welcome

Thanks in advance.
Radha
#AIX-Forum