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

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Date:   Wed, 25 Jan 2017 15:32:11 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] kasan: Respect /proc/sys/kernel/traceoff_on_warning

On Wed, Jan 25, 2017 at 3:28 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, Jan 25, 2017 at 03:25:24PM +0100, Peter Zijlstra wrote:
>>
>> After much waiting I finally reproduced a KASAN issue, only to find my
>> trace-buffer empty of useful information because it got spooled out :/
>>
>> Make kasan_report honour the /proc/sys/kernel/traceoff_on_warning
>> interface.
>>
>> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>> ---
>
> Seems to compile better when you add the required header files...
>
>  mm/kasan/report.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index b82b3e2..3653ed1 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -24,6 +24,7 @@
>  #include <linux/types.h>
>  #include <linux/kasan.h>
>  #include <linux/module.h>
> +#include <linux/ftrace.h>
>
>  #include <asm/sections.h>
>
> @@ -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?
Note that KASAN errors are not fatal, and the first one may possibly
occur quite early.
>         info.access_addr = (void *)addr;
>         info.access_size = size;
>         info.is_write = is_write;



-- 
Alexander Potapenko
Software Engineer

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