On Fri, 13 Feb 2015, Josh Poimboeuf wrote: > > How about we take a slightly different aproach -- put a probe (or ftrace) > > on __switch_to() during a klp transition period, and examine stacktraces > > for tasks that are just about to start running from there? > > > > The only tasks that would not be covered by this would be purely CPU-bound > > tasks that never schedule. But we are likely in trouble with those anyway, > > because odds are that non-rescheduling CPU-bound tasks are also > > RT-priority tasks running on isolated CPUs, which we will fail to handle > > anyway. > > > > I think Masami used similar trick in his kpatch-without-stopmachine > > aproach. > > Yeah, that's definitely an option, though I'm really not too crazy about > it. Hooking into the scheduler is kind of scary and disruptive. This is basically about running a stack checking for ->next before switching to it, i.e. read-only operation (admittedly inducing some latency, but that's the same with locking the runqueue). And only when in transition phase. > We'd also have to wake up all the sleeping processes. Yes, I don't think there is a way around that. Thanks, -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
