Re: [PATCH 19/32] kmsan: Accept ranges starting with 0 on s390

[Alexander Potapenko]

On Wed, Nov 15, 2023 at 9:34 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote:
>
> On s390 the virtual address 0 is valid (current CPU's lowcore is mapped
> there), therefore KMSAN should not complain about it.
>
> Disable the respective check on s390. There doesn't seem to be a
> Kconfig option to describe this situation, so explicitly check for
> s390.
>
> Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
(see the nit below)

> ---
>  mm/kmsan/init.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/kmsan/init.c b/mm/kmsan/init.c
> index ffedf4dbc49d..14f4a432fddd 100644
> --- a/mm/kmsan/init.c
> +++ b/mm/kmsan/init.c
> @@ -33,7 +33,9 @@ static void __init kmsan_record_future_shadow_range(void *start, void *end)
>         bool merged = false;
>
>         KMSAN_WARN_ON(future_index == NUM_FUTURE_RANGES);
> -       KMSAN_WARN_ON((nstart >= nend) || !nstart || !nend);
> +       KMSAN_WARN_ON((nstart >= nend) ||
> +                     (!IS_ENABLED(CONFIG_S390) && !nstart) ||
Please add a comment explaining this bit.

> +                     !nend);
>         nstart = ALIGN_DOWN(nstart, PAGE_SIZE);
>         nend = ALIGN(nend, PAGE_SIZE);
>
> --
> 2.41.0
>