#0  __GI___pthread_mutex_lock (mutex=0x0) at ../nptl/pthread_mutex_lock.c:66
        __PRETTY_FUNCTION__ = "__pthread_mutex_lock"
        type = 2166301712
#1  0x00007f806f7200d4 in stubSyncThreadProc (ThreadSelf=0x96ced0, pvUser=<optimized out>) at /build/buildd/virtualbox-4.3.10-dfsg/src/VBox/Additions/common/crOpenGL/load.c:898
No locals.
#2  0x00007f806f74172c in rtThreadMain (pThread=0x96ced0, NativeThread=<optimized out>, pszThreadName=<optimized out>) at /build/buildd/virtualbox-4.3.10-dfsg/src/VBox/Runtime/common/misc/thread.cpp:712
        rc = <optimized out>
#3  0x00007f806f745bbc in rtThreadNativeMain (pvArgs=0x96ced0) at /build/buildd/virtualbox-4.3.10-dfsg/src/VBox/Runtime/r3/posix/thread-posix.cpp:324
        pThread = 0x96ced0
        Self = 140189580969728
        rc = <optimized out>
        __PRETTY_FUNCTION__ = "void* rtThreadNativeMain(void*)"
#4  0x00007f80811f0182 in start_thread (arg=0x7f806e2cc700) at pthread_create.c:312
        __res = <optimized out>
        pd = 0x7f806e2cc700
        now = <optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140189580969728, 4071172320343756491, 0, 0, 140189580970432, 140189580969728, -4071418995318845749, -4071615141984858421}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
        not_first_call = <optimized out>
        pagesize_m1 = <optimized out>
        sp = <optimized out>
        freesize = <optimized out>
        __PRETTY_FUNCTION__ = "start_thread"
#5  0x00007f808269e47d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
No locals.