So, I added a gdb backtrace, I guess the interesting part is:

---8<-------------
Thread 31 (Thread 0xe04e8b40 (LWP 26311)):
#0  0xf7fd9be5 in __kernel_vsyscall ()
No symbol table info available.
#1  0xf478025c in pthread_cond_wait@@GLIBC_2.3.2 () from
/lib/i386-linux-gnu/libpthread.so.0
No symbol table info available.
#2  0xe2e9cabc in radeon_drm_cs_emit_ioctl (param=0x8386300) at
../../../../../../../include/c11/threads_posix.h:159
        ws = 0x8386300
        cs = <optimized out>
        i = <optimized out>
#3  0xe2e9c117 in impl_thrd_routine (p=0x856a708) at
../../../../../../../include/c11/threads_posix.h:87
        pack = {func = 0xe2e9ca60 <radeon_drm_cs_emit_ioctl>, arg = 0x8386300}
#4  0xf477b1aa in start_thread () from /lib/i386-linux-gnu/libpthread.so.0
No symbol table info available.
#5  0xf44b5fde in clone () from /lib/i386-linux-gnu/libc.so.6
------------->8---