Messages in this thread |  | | Date | Fri, 13 Feb 2015 15:22:15 +0100 (CET) | From | Jiri Kosina <> | Subject | Re: [RFC PATCH 0/9] livepatch: consistency model |
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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
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