Re: [PATCH 1/5] kmsan: core: kmsan_in_runtime() should return true in NMI context

Peter Zijlstra
2022-11-02T12:52:41Z

On Wed, Nov 02, 2022 at 12:06:07PM +0100, Alexander Potapenko wrote:
> Without that, every call to __msan_poison_alloca() in NMI may end up
> allocating memory, which is NMI-unsafe.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/
> Signed-off-by: Alexander Potapenko <glider@google.com>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> ---
> mm/kmsan/kmsan.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/kmsan/kmsan.h b/mm/kmsan/kmsan.h
> index 961eb658020aa..3cd2050a33e6a 100644
> --- a/mm/kmsan/kmsan.h
> +++ b/mm/kmsan/kmsan.h
> @@ -125,6 +125,8 @@ static __always_inline bool kmsan_in_runtime(void)
> {
> if ((hardirq_count() >> HARDIRQ_SHIFT) > 1)
> return true;
> + if (in_nmi())
> + return true;
> return kmsan_get_context()->kmsan_in_runtime;
> }
>
> --
> 2.38.1.273.g43a17bfeac-goog
>