linux-kernel - Re: [PATCH v3 01/12] lib/kasan: introduce CONFIG_ARCH_DEFER

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Message-ID: <d5c96fb8-84b2-46de-8f1f-db53d7ed7309-agordeev@linux.ibm.com>
Date: Fri, 18 Jul 2025 14:38:55 +0200
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Sabyrzhan Tasbolatov <snovitoll@...il.com>
Cc: hca@...ux.ibm.com, christophe.leroy@...roup.eu, andreyknvl@...il.com,
        akpm@...ux-foundation.org, ryabinin.a.a@...il.com, glider@...gle.com,
        dvyukov@...gle.com, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
        linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-um@...ts.infradead.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v3 01/12] lib/kasan: introduce CONFIG_ARCH_DEFER_KASAN
 option

On Thu, Jul 17, 2025 at 07:27:21PM +0500, Sabyrzhan Tasbolatov wrote:
> Introduce CONFIG_ARCH_DEFER_KASAN to identify architectures that need
> to defer KASAN initialization until shadow memory is properly set up.
> 
> Some architectures (like PowerPC with radix MMU) need to set up their
> shadow memory mappings before KASAN can be safely enabled, while others
> (like s390, x86, arm) can enable KASAN much earlier or even from the
> beginning.
> 
> This option allows us to:
> 1. Use static keys only where needed (avoiding overhead)
> 2. Use compile-time constants for arch that don't need runtime checks
> 3. Maintain optimal performance for both scenarios
> 
> Architectures that need deferred KASAN should select this option.
> Architectures that can enable KASAN early will get compile-time
> optimizations instead of runtime checks.
> 
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
> ---
> Changes in v3:
> - Introduced CONFIG_ARCH_DEFER_KASAN to control static key usage
> ---
>  lib/Kconfig.kasan | 8 ++++++++
>  1 file changed, 8 insertions(+)

Acked-by: Alexander Gordeev <agordeev@...ux.ibm.com> # s390