[openib-general] ptrace peektext failure for Mellanox IBGD 1.7.0 based cluster

[David Lecomber]

Dear all,

I'm having a kernel problem which I believe to be caused by the
infiniband drivers on the system I am using.

Kernel 2.6.11, Mellanox software stack IBGD 1.7.0.

Essentially, once an MPI code is started, the kernel refuses to allow
ptrace() access to the text segment (ie. where the program instructions
lie), although it is possible to access the data segment.

This means debugging is impossible (gdb, idb, ddt, etc.).

The attached code demonstrates the problem.

Untar, and then make.  Run the 'mpi' program, and pick a line of it's
output, paste into another shell.  On the standard, non MPI test code,
the ptrace reads are all successful.  On the MPI test, it gives an error
for the text segment reads..

Is this a known issue - are there any upgrades/fixes which should have
been applied?  I would appreciate if someone could run the test
suggested on a really new setup, and see if the error happens.


Regards
David
-- 
David Lecomber, CTO, Allinea Software
tel: +44 1926 623231  fax: +44 1926 623232

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