Please help me understand this stack trace

[Bryan Ischo <bryan at ischo dot com>]

Hi there, I am experiencing an occasional deadlock that I believe is due 
to an Nvidia driver problem.  My program attempts to do a fork()/exec() 
sequence from a thread that does not have a GLX context.  As far as I 
know this is perfectly legal but some sort of trickery in Nvidia's 
OpenGL library is somehow intercepting the fork and then causing a 
deadlock.  Here is the stack trace in the process that deadlocks 
(portions above the fork() call ommitted):

Thread 1 (Thread 0x7f217f9fb7c0 (LWP 1402)):
#0  0x00007f217d7a400c in __lll_lock_wait () from /lib/libpthread.so.0
#1  0x00007f217d79fee7 in _L_lock_560 () from /lib/libpthread.so.0
#2  0x00007f217d79fd79 in pthread_mutex_lock () from /lib/libpthread.so.0
#3  0x00007f217e80d9ec in ?? () from /usr/lib/libGL.so.1
#4  0x00007f217ad975e4 in ?? () from /usr/lib/libnvidia-glcore.so.295.53
#5  0x00007f217e7efe2c in ?? () from /usr/lib/libGL.so.1
#6  0x00007f217e7f060e in ?? () from /usr/lib/libGL.so.1
#7  0x00007f217da67d56 in fork () from /lib/libc.so.6

Note that this is in the child process; apparently fork() has already 
succeeded in cloning the parent process into a child, but after that it 
calls into some unnamed function in /usr/lib/libGL.so.1.

I simply cannot understand how libc's fork() function is calling into 
the OpenGL library.  By what mechanism might this be occurring?  Is 
there some kind of fork hook that I am unaware of that NVidia is using 
to register a callback during fork()?  I suspected pthread_atfork() and 
I attempted unsuccessfully to "override" pthread_atfork by creating my 
own dummy implementation thereof, building a shared object library out 
of it, and using LD_PRELOAD to force my version to be used.  Since I 
have never done this before, I can't be certain that I did everything 
correctly; my pthread_atfork() function was never called in any case, 
and this attempt did not fix the problem.

Does anyone have any creative ideas on how I can prevent glibc fork() 
from calling into the NVidia OpenGL library?

I am running glibc version 2.15 on an AMD64 architecture system (Intel 
E5540).  Nvidia driver version is 295.53.

uname -a:

Linux <redacted> 3.3.7-1-ARCH #1 SMP PREEMPT Tue May 22 00:26:26 CEST 
2012 x86_64 GNU/Linux

Thank you and best wishes!
Bryan