var runtime.extraM

4 uses

	runtime (current package)
		proc.go#L2604: 	extraM atomic.Uintptr
		proc.go#L2626: 		old := extraM.Load()
		proc.go#L2642: 		if extraM.CompareAndSwap(old, locked) {
		proc.go#L2653: 	extraM.Store(uintptr(unsafe.Pointer(mp)))