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Please help me understand this stack trace

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/
#1  0x00007f217d79fee7 in _L_lock_560 () from /lib/
#2  0x00007f217d79fd79 in pthread_mutex_lock () from /lib/
#3  0x00007f217e80d9ec in ?? () from /usr/lib/
#4  0x00007f217ad975e4 in ?? () from /usr/lib/
#5  0x00007f217e7efe2c in ?? () from /usr/lib/
#6  0x00007f217e7f060e in ?? () from /usr/lib/
#7  0x00007f217da67d56 in fork () from /lib/

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/

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!

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