_KASAN_SHADOW_START
#define KASAN_SHADOW_START _KASAN_SHADOW_START(vabits_actual)
BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), SHADOW_ALIGN));
BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), SHADOW_ALIGN));