VM_STACK_FLAGS    258 fs/exec.c      	vma->vm_flags = VM_STACK_FLAGS;
VM_STACK_FLAGS    622 fs/exec.c      	vm_flags = VM_STACK_FLAGS;
VM_STACK_FLAGS    895 mm/mmap.c      		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);