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Re: Query regarding synchronize_sched_expedited and resched_cpu

From Byungchul Park <byungchul.park@lge.com>
Newsgroups linux.kernel
Subject Re: Query regarding synchronize_sched_expedited and resched_cpu
Date 2017-09-19 04:00 +0200
Message-ID <urfZn-66X-3@gated-at.bofh.it> (permalink)
References (3 earlier) <ur603-7Z6-49@gated-at.bofh.it> <ur6Mr-8un-51@gated-at.bofh.it> <ur6W7-7F-27@gated-at.bofh.it> <ur75M-b2-41@gated-at.bofh.it> <ur75M-b2-39@gated-at.bofh.it>
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On Mon, Sep 18, 2017 at 12:29:31PM -0400, Steven Rostedt wrote:
> On Mon, 18 Sep 2017 09:24:12 -0700
> "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> 
> 
> > As soon as I work through the backlog of lockdep complaints that
> > appeared in the last merge window...  :-(
> > 
> > sparse_irq_lock, I am looking at you!!!  ;-)
> 
> I just hit one too, and decided to write a patch to show a chain of 3
> when applicable.

Hello Steven,

I really agree with this. Currently, in case that more than two locks
participates in a deadlock, the report informs insuffucuently.

Thanks,
Byungchul

> 
> For example:
> 
>  Chain exists of:
>    cpu_hotplug_lock.rw_sem --> smpboot_threads_lock --> (complete)&self->parked
>  
>   Possible unsafe locking scenario by crosslock:
>  
>         CPU0                    CPU1                    CPU2
>         ----                    ----                    ----
>    lock(smpboot_threads_lock);
>    lock((complete)&self->parked);
>                                 lock(cpu_hotplug_lock.rw_sem);
>                                 lock(smpboot_threads_lock);
>                                                        lock(cpu_hotplug_lock.rw_sem);
>                                                        unlock((complete)&self->parked);
>  
>   *** DEADLOCK ***
> 
> :-)
> 
> -- Steve

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Thread

Query regarding synchronize_sched_expedited and resched_cpu Neeraj Upadhyay <neeraju@codeaurora.org> - 2017-09-15 13:20 +0200
  Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-17 03:10 +0200
    Re: Query regarding synchronize_sched_expedited and resched_cpu Neeraj Upadhyay <neeraju@codeaurora.org> - 2017-09-17 08:10 +0200
      Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-18 17:20 +0200
        Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-18 18:10 +0200
          Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-18 18:20 +0200
            Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-18 18:30 +0200
              Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-18 19:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 02:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 03:30 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 04:30 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Byungchul Park <byungchul.park@lge.com> - 2017-09-19 04:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Byungchul Park <byungchul.park@lge.com> - 2017-09-19 04:10 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 04:40 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Byungchul Park <byungchul.park@lge.com> - 2017-09-19 04:50 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 06:10 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Boqun Feng <boqun.feng@gmail.com> - 2017-09-19 07:40 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Mike Galbraith <efault@gmx.de> - 2017-09-19 08:20 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Byungchul Park <byungchul.park@lge.com> - 2017-09-19 09:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 15:50 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Peter Zijlstra <peterz@infradead.org> - 2017-09-21 16:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-21 17:40 +0200
              Re: Query regarding synchronize_sched_expedited and resched_cpu Byungchul Park <byungchul.park@lge.com> - 2017-09-19 04:00 +0200
            Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-18 18:30 +0200
              Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 17:40 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-19 18:00 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-19 18:20 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Peter Zijlstra <peterz@infradead.org> - 2017-09-21 16:10 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-21 18:10 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu Peter Zijlstra <peterz@infradead.org> - 2017-09-21 18:40 +0200
                Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-21 18:50 +0200
        Re: Query regarding synchronize_sched_expedited and resched_cpu Peter Zijlstra <peterz@infradead.org> - 2017-09-21 16:00 +0200
          Re: Query regarding synchronize_sched_expedited and resched_cpu "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-09-21 17:40 +0200
            Re: Query regarding synchronize_sched_expedited and resched_cpu Peter Zijlstra <peterz@infradead.org> - 2017-09-21 18:20 +0200
          Re: Query regarding synchronize_sched_expedited and resched_cpu Steven Rostedt <rostedt@goodmis.org> - 2017-09-21 17:50 +0200

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