Hi,

I currently do not have subscribed to LKML, so please CC to my address when 
answering. I will browse the archive, but on a not so regular basis.

I came across a strange behavior of mmap using the ACE library. After some 
discussion on the ace-users mailing list 
(http://groups.yahoo.com/group/ace-users/message/36897) I'd like to post this 
question here in the hope that anyone knows more about this.

The problem basically is that a program doing a mmap call with the MAP_FIXED 
flag set crashes just by unmapping and mapping of an extended (larger) memory 
area. Note it crashes although it never touches (writes) to the memory it 
maps.

Attached is a C file that if compiled and run on a 2.4.x Kernel crashes with a 
segmentation fault.  If called with any argument it uses a (delta) value to 
increase the map size, so it crashes after 21 iterations on my computer.
My kernel version is:
$ cat /proc/version
Linux version 2.4.20-18.9.acpi.4 (dsanta@ltspc67.epfl.ch) (gcc version 3.2.2 
20030222 (Red Hat Linux 3.2.2-5)) #1 Wed Jul 2 14:54:57 CEST 2003

If anyone knows why the program crashes instead of just failing with some 
error code, please let me know.

The attached program is a slightly modified version I got from an ACE 
developer
> Here's my test program. It fails under all machines that I have tested.
> Maybe you can post it to Linux Kernel and ask what is broken and tell me if
> you get any answer. 

Lothar
-- 
Lothar Werzinger Dipl.-Ing. Univ.
framework & platform architect
Xcerla Corporation
275 Tennant Avenue, Suite 202
Morgan Hill, Ca 95037
email: lothar@xcerla.com
phone: +1-408-776-9018