linux-kernel - Re: [PATCH] kasan: Respect /proc/sys/kernel/traceoff_on

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Message-ID: <20170130141808.408c5241@gandalf.local.home>
Date:   Mon, 30 Jan 2017 14:18:08 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kasan: Respect /proc/sys/kernel/traceoff_on_warning

On Wed, 25 Jan 2017 15:35:32 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> On Wed, Jan 25, 2017 at 03:32:11PM +0100, Alexander Potapenko wrote:
> 
> > > @@ -300,6 +301,8 @@ void kasan_report(unsigned long addr, size_t size,
> > >         if (likely(!kasan_report_enabled()))
> > >                 return;
> > >
> > > +       disable_trace_on_warning();
> > > +  
> > Who is going to enable tracing back after we're done?  
> 
> The user..

Yep,

 # echo 1 > /sys/kernel/debug/tracing/tracing_on

Re-enables tracing.

-- Steve

> 
> > Note that KASAN errors are not fatal, and the first one may possibly
> > occur quite early.  
> 
> WARN*() isn't fatal either, and it does the same thing. Note that
> traceoff_on_warning is default disabled. You have to explicitly request
> this.