glxgears[4186]: segfault at ffffffffffffffff ip 000078805fc4b901 sp
00007ce9598e21c0 error 7 in nouveau_dri.so[78805f7d1000+136c000]

Stracing it revealed that the crash happens after a mmap(NULL, 10485760,
PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE,MAP_ANONYMOUS, -1, 0) syscall
returns -1.

I think it might be caused by the return value of mmap not being checked in
src/gallium/auxiliary/rtasm/rtasm_execmem.c, leading to the the memory being
accessed somewhere else.

So it probably needs some

  if (exec_mem == MAP_FAILED)

check somewhere.

PS: Sorry if this is not the correct component.