I915_VMA_PIN_OVERFLOW
if (WARN_ON(bound & I915_VMA_PIN_OVERFLOW)) {
BUILD_BUG_ON(PIN_MBZ != I915_VMA_PIN_OVERFLOW);
GEM_BUG_ON(vma->flags & I915_VMA_PIN_OVERFLOW);
#define I915_VMA_BIND_MASK (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND | I915_VMA_PIN_OVERFLOW)