Re: [BUG] perf and kmemcheck : fatal combination

[Pekka Enberg]

On Tue, Apr 26, 2011 at 10:38 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> On Mon, 2011-04-25 at 18:08 +0200, Eric Dumazet wrote:
>> Hi guys
>>
>> Just got a panic on a kmemcheck kernel, latest linux-2.6 tree.
>>
>> I forgot I had kmemcheck enabled, and started "perf top" just because my
>> machine was damn slow... Oh well...
>>
>> Crash in do_nmi -> nmi_enter() -> BUG_ON(in_nmi());
>
> Hmm,. I bet because kmemcheck triggers faults from nmi context because
> it messes about with the page protection bits a lot to track things.
>
> Can't really think of anything except not making perf available on
> kmemcheck kernels.
>
> ---
>  init/Kconfig |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 32745bf..94735b4 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1125,6 +1125,7 @@ config PERF_EVENTS
>        bool "Kernel performance events and counters"
>        default y if (PROFILING || PERF_COUNTERS)
>        depends on HAVE_PERF_EVENTS
> +       depends on !KMEMCHECK
>        select ANON_INODES
>        select IRQ_WORK
>        help

Acked-by: Pekka Enberg <penberg@xxxxxxxxxx>
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