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

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Date:   Thu, 16 Feb 2017 13:25:00 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Russell King <rmk@...linux.org.uk>
Subject: Re: Regression in next with use printk_safe buffers in printk

On (02/15/17 20:03), Tony Lindgren wrote:
> * Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> [170215 17:32]:
> > On (02/15/17 10:01), Tony Lindgren wrote:
> > [..]
> > > Below is another issue I noticed caused by commit f975237b7682 that
> > > I noticed during booting.
> > 
> > do you mean that with f975237b7682 you _always_ see that illegal RCU
> > usage warning?
> 
> Yeah on every boot on devices using cpuidle_coupled.

does this mean that with the printk-safe patches reverted
(so, basically, the same conditions module 4 printk patches)
you don't see illegal RCU usage reports? at the moment I can't
see any connection between f975237b7682 and RCU usage from idle CPU.

[..]

> > ---
> > 
> > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> > index 7180088cbb23..34da86e73d00 100644
> > --- a/kernel/printk/printk.c
> > +++ b/kernel/printk/printk.c
> > @@ -1563,7 +1563,7 @@ static void call_console_drivers(const char *ext_text, size_t ext_len,
> >  {
> >  	struct console *con;
> >  
> > -	trace_console(text, len);
> > +	trace_console_rcuidle(text, len);
> >  
> >  	if (!console_drivers)
> >  		return;
> > 
> > ---
> > 
> > 
> > I need to look more at this.
> 
> That fixes it for me thanks, so feel free to add:
> 
> Tested-by: Tony Lindgren <tony@...mide.com>

thanks.

	-ss