linux-kernel - Re: Regression in next with use printk

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Message-ID: <20170215044444.GA1834@jagdpanzerIV.localdomain>
Date:   Wed, 15 Feb 2017 13:44:44 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        John Stultz <john.stultz@...aro.org>
Subject: Re: Regression in next with use printk_safe buffers in printk

On (02/14/17 09:03), Tony Lindgren wrote:
[..]
> > Do not call printk() from tk_debug_account_sleep_time(), because
> > tk_debug_account_sleep_time() is called under tk_core seq lock.
> > It's not safe to call printk() under tk_core, because console_sem
> > invokes scheduled (via wake_up_process()->activate_task()), which,
> > in turn, can call timekeeping code again, for instance, via
> > get_time()->ktime_get(). This may result in infinite loop on
> > tk_core.
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> 
> Thanks yeah this fixes the issue for me:
> 
> Tested-by: Tony Lindgren <tony@...mide.com>

thanks.

	-ss