From: Peter Zijlstra <peterz@infradead.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>, Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-pm@vger.kernel.org
Subject: Re: Regression in next with use printk_safe buffers in printk
Date: Tue, 14 Feb 2017 17:18:09 +0100 [thread overview]
Message-ID: <20170214161809.GQ6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20170214160140.GA401@tigerII.localdomain>
On Wed, Feb 15, 2017 at 01:01:40AM +0900, Sergey Senozhatsky wrote:
>
> but I'm a bit confused by rt_b->rt_runtime_lock in this unsafe lock
> scenario (so it's not ABBA, but ABAD)
>
> > lock(hrtimer_bases.lock);
> > lock(&rt_b->rt_runtime_lock);
> > lock(hrtimer_bases.lock);
> > lock(tk_core);
> >
> >
> > Chain exists of:
> >
> > tk_core --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock
>
>
> I'm lacking some knowledge here, sorry. where does the tk_core --> &rt_b->rt_runtime_lock
> come from?
rt_b->rt_runtime_lock is one of the scheduler locks, since we do
printk() under tk_core, which does semaphore muck, which then includes
the entire scheduler chain of locks.
next prev parent reply other threads:[~2017-02-14 16:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 18:59 Regression in next with use printk_safe buffers in printk Tony Lindgren
2017-02-14 16:01 ` Sergey Senozhatsky
2017-02-14 16:18 ` Peter Zijlstra [this message]
2017-02-14 16:56 ` Sergey Senozhatsky
2017-02-14 17:03 ` Tony Lindgren
2017-02-15 4:44 ` Sergey Senozhatsky
2017-02-14 18:29 ` Peter Zijlstra
2017-02-15 4:49 ` Sergey Senozhatsky
2017-02-14 16:54 ` Tony Lindgren
2017-02-15 18:01 ` Tony Lindgren
2017-02-16 1:31 ` Sergey Senozhatsky
2017-02-16 4:03 ` Tony Lindgren
2017-02-16 4:25 ` Sergey Senozhatsky
2017-02-16 15:10 ` Tony Lindgren
2017-02-16 16:31 ` Sergey Senozhatsky
2017-02-16 19:13 ` Tony Lindgren
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