When tracing is enabled, kstop_machine is called to prevent
races with the CPUS executing code being modified (which can
-cause the CPU to do undesireable things), and the nops are
+cause the CPU to do undesirable things), and the nops are
patched back to calls. But this time, they do not call mcount
(which is just a function stub). They now call into the ftrace
infrastructure.