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[94.189.142.142]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aec6ca7ea53sm757005366b.133.2025.07.21.16.19.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Jul 2025 16:19:12 -0700 (PDT) Message-ID: Date: Tue, 22 Jul 2025 01:18:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 01/12] lib/kasan: introduce CONFIG_ARCH_DEFER_KASAN option To: Andrew Morton , Sabyrzhan Tasbolatov Cc: hca@linux.ibm.com, christophe.leroy@csgroup.eu, andreyknvl@gmail.com, agordeev@linux.ibm.com, glider@google.com, dvyukov@google.com, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-mm@kvack.org References: <20250717142732.292822-1-snovitoll@gmail.com> <20250717142732.292822-2-snovitoll@gmail.com> <20250717151048.bb6124bea54a31cd2b41faaf@linux-foundation.org> Content-Language: en-US From: Andrey Ryabinin In-Reply-To: <20250717151048.bb6124bea54a31cd2b41faaf@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/18/25 12:10 AM, Andrew Morton wrote: > On Thu, 17 Jul 2025 19:27:21 +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. > > Looks nice and appears quite mature. I'm reluctant to add it to mm.git > during -rc6, especially given the lack of formal review and ack tags. > > But but but, that's what the mm-new branch is for. I guess I'll add it > to get some additional exposure, but whether I'll advance it into > mm-unstable/linux-next for this cycle is unclear. > > What do you (and others) think? After looking a bit, it breaks UM and probably LoongArch too. I'd say it needs more work and not ready even for mm-new.