Re: sched: serial port lockdep warning when offlining CPUs

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: sched: serial port lockdep warning when offlining CPUs
Date	2017-09-28 14:10 +0200
Message-ID	<uuFND-nv-13@gated-at.bofh.it> (permalink)
References	(1 earlier) <uuDsv-7h4-19@gated-at.bofh.it> <uuEoy-7PA-17@gated-at.bofh.it> <uuFkC-8pL-25@gated-at.bofh.it> <uuFDX-8w4-9@gated-at.bofh.it> <uuFND-nv-1@gated-at.bofh.it>
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On Thu, Sep 28, 2017 at 02:05:32PM +0200, Peter Zijlstra wrote:
> (please linewrap normal text at 72 chars)
> 
> On Thu, Sep 28, 2017 at 11:45:30AM +0000, Levin, Alexander (Sasha Levin) wrote:
> > Okay, that seems to have delt with the callbacks supressed issue.
> > 
> > I also seem to be hitting it as a result of the scheduler triggering a
> > WARN, where print_stack_trace(), for example, just uses printk().
> > 
> > Now I'm not sure what's your approach here, do we keep converting
> > printk to printk_deferred one by one until we whacked every mole?
> 
> Nah.. WARN's _should_ not trigger. If they do we fix that.
> 
> Getting a lockdep splat after a WARN is something I can live with.
> 
> And you really don't want that deferred nonsense for WARNs, because that
> means you'll risk not over getting the output.

Note that I'm not likely to care too much either way, because I'm simply
not using any of that printk() nonsense ;-)


I'll repost my patches now; otherwise I'll forget again anyway.

Thread

sched: serial port lockdep warning when offlining CPUs Sasha Levin <levinsasha928@gmail.com> - 2017-09-28 11:30 +0200
  Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 11:40 +0200
    Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 12:40 +0200
      Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 13:40 +0200
        Re: sched: serial port lockdep warning when offlining CPUs "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-28 14:00 +0200
          Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 14:00 +0200
          Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 14:10 +0200
            Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 14:10 +0200
              Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 14:20 +0200
                Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 14:30 +0200
      Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 13:50 +0200
        Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 14:00 +0200
    Re: sched: serial port lockdep warning when offlining CPUs "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-09-28 13:10 +0200
      Re: sched: serial port lockdep warning when offlining CPUs Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 13:20 +0200
        Re: sched: serial port lockdep warning when offlining CPUs Peter Zijlstra <peterz@infradead.org> - 2017-09-28 13:40 +0200

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