linux-kernel - Re: [PATCH] trace: skip hwasan

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Date:   Mon, 18 Feb 2019 16:25:45 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Qian Cai <cai@....pw>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] trace: skip hwasan

On Sun, Feb 17, 2019 at 5:34 AM Qian Cai <cai@....pw> wrote:
>
> Enabling function tracer with CONFIG_KASAN_SW_TAGS=y (hwasan) tracer
> causes the whole system frozen on ThunderX2 systems with 256 CPUs,
> because there is a burst of too much pointer access, and then KASAN will
> dereference each byte of the shadow address for the tag checking which
> will kill all the CPUs.

Hi Qian,

Could you check if adding "CFLAGS_REMOVE_tags.o = -pg" into
mm/kasan/Makefile helps with that?

Thanks!

>
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>  kernel/trace/Makefile | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index c2b2148bb1d2..fdd547a68385 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -28,6 +28,11 @@ ifdef CONFIG_GCOV_PROFILE_FTRACE
>  GCOV_PROFILE := y
>  endif
>
> +# Too much pointer access will kill hwasan.
> +ifdef CONFIG_KASAN_SW_TAGS
> +KASAN_SANITIZE := n
> +endif
> +
>  CFLAGS_trace_benchmark.o := -I$(src)
>  CFLAGS_trace_events_filter.o := -I$(src)
>
> --
> 2.17.2 (Apple Git-113)
>