var runtime.extraM

4 uses

	runtime (current package)
		proc.go#L2744: 	extraM atomic.Uintptr
		proc.go#L2766: 		old := extraM.Load()
		proc.go#L2782: 		if extraM.CompareAndSwap(old, locked) {
		proc.go#L2793: 	extraM.Store(uintptr(unsafe.Pointer(mp)))