(gdb) thread apply all bt

Thread 2 (Thread 0x7f4402a4f700 (LWP 29777)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f44039d7797 in cnd_wait (cond=0x19c7ed0, mtx=0x19c7ea8) at ../../../../../include/c11/threads_posix.h:152
#2  0x00007f44039d7b33 in pipe_semaphore_wait (sema=0x19c7ea8) at ../../../../../src/gallium/auxiliary/os/os_thread.h:248
#3  0x00007f44039e00b2 in radeon_drm_cs_emit_ioctl (param=0x19c7bc0) at radeon_drm_winsys.c:591
#4  0x00007f44039d76bc in impl_thrd_routine (p=0x19c8340) at ../../../../../include/c11/threads_posix.h:85
#5  0x00007f440a1881f1 in start_thread (arg=0x7f4402a4f700) at pthread_create.c:309
#6  0x00007f4408e68eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7f440af89880 (LWP 29774)):
#0  0x00007f4408e61d63 in select () at ../sysdeps/unix/syscall-template.S:81
#1  0x000000000060f76d in WaitForSomething (pClientsReady=0x2786410) at /var/tmp/portage/x11-base/xorg-server-1.15.0/work/xorg-server-1.15.0/os/WaitFor.c:226
#2  0x0000000000432578 in Dispatch () at /var/tmp/portage/x11-base/xorg-server-1.15.0/work/xorg-server-1.15.0/dix/dispatch.c:362
#3  0x000000000044063a in dix_main (argc=10, argv=0x7fffaf0ac888, envp=0x7fffaf0ac8e0) at /var/tmp/portage/x11-base/xorg-server-1.15.0/work/xorg-server-1.15.0/dix/main.c:294
#4  0x0000000000422e55 in main (argc=10, argv=0x7fffaf0ac888, envp=0x7fffaf0ac8e0) at /var/tmp/portage/x11-base/xorg-server-1.15.0/work/xorg-server-1.15.0/dix/stubmain.c:34