rb_entry_safe
return rb_entry_safe(rb, struct drm_mm_node, rb_hole_size);
return rb_entry_safe(rb, struct drm_mm_node, rb_hole_addr);
for ((x) = rb_entry_safe(__rb_deepest_left((head)->rb_node), \
rb_entry_safe(rb_next_postorder(&x->member), typeof(*x), member), 1); \