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

From	Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups	linux.kernel
Subject	Re: livepatch: change to a per-task consistency model
Date	2016-05-18 19:00 +0200
Message-ID	<rAcZc-4DW-31@gated-at.bofh.it> (permalink)
References	<rt12N-1W5-3@gated-at.bofh.it> <rt12O-1W5-9@gated-at.bofh.it> <rzW81-2af-13@gated-at.bofh.it> <rA4RX-7UR-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

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

Thread

Re: livepatch: change to a per-task consistency model Jessica Yu <jeyu@redhat.com> - 2016-05-18 01:00 +0200
  Re: livepatch: change to a per-task consistency model Jiri Kosina <jikos@kernel.org> - 2016-05-18 10:20 +0200
    Re: livepatch: change to a per-task consistency model Josh Poimboeuf <jpoimboe@redhat.com> - 2016-05-18 19:00 +0200
      Re: livepatch: change to a per-task consistency model Jiri Kosina <jikos@kernel.org> - 2016-05-18 22:30 +0200
        RE: livepatch: change to a per-task consistency model David Laight <David.Laight@ACULAB.COM> - 2016-05-23 11:50 +0200
          RE: livepatch: change to a per-task consistency model Jiri Kosina <jikos@kernel.org> - 2016-05-23 20:50 +0200
            RE: livepatch: change to a per-task consistency model David Laight <David.Laight@ACULAB.COM> - 2016-05-24 17:10 +0200
              RE: livepatch: change to a per-task consistency model Jiri Kosina <jikos@kernel.org> - 2016-05-25 00:50 +0200

csiph-web