Re: livepatch: change to a per-task consistency model

Josh Poimboeuf
2016-05-18T16:52:06Z

On Wed, May 18, 2016 at 10:16:22AM +0200, Jiri Kosina wrote:
> On Tue, 17 May 2016, Jessica Yu wrote:
>
> > What about tasks sleeping on affected functions in uninterruptible sleep
> > (possibly indefinitely)? Since all signals are ignored, we wouldn't be
> > able to patch those tasks in this way, right? Would that be an
> > unsupported case?
>
> I don't think there is any better way out of this situation than
> documenting that the convergence of patching could in such cases could
> take quite a lot of time (well, we can pro-actively try to detect this
> situation before the patching actually start, and warn about the possible
> consequences).
>
> But let's face it, this should be pretty uncommon, because (a) it's not
> realistic for the wait times to be really indefinite (b) the task is
> likely to be in TASK_KILLABLE rather than just plain TASK_UNINTERRUPTIBLE.

Yeah, I think this situation -- a task sleeping on an affected function
in uninterruptible state for a long period of time -- would be
exceedingly rare and not something we need to worry about for now.

--
Josh