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b=JnFTsEv6asV1QHvn9oyLm0adlVD8YAwUk8D9+xSBsZ/4xRhcX7l4l0qMZNDgSRPEr VDRVgiNcFppstl5irHVMQqIlu2EyZC6EiTz9tDOSSNke5t727uDO0ipCsMi5ieUTgf xIAtuMC6pkfxnueF+6ZvQa0PYivWUcYkQ1GV4da4= Date: Thu, 17 Jul 2025 15:10:48 -0700 From: Andrew Morton To: Sabyrzhan Tasbolatov Cc: hca@linux.ibm.com, christophe.leroy@csgroup.eu, andreyknvl@gmail.com, agordeev@linux.ibm.com, ryabinin.a.a@gmail.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 Subject: Re: [PATCH v3 01/12] lib/kasan: introduce CONFIG_ARCH_DEFER_KASAN option Message-Id: <20250717151048.bb6124bea54a31cd2b41faaf@linux-foundation.org> In-Reply-To: <20250717142732.292822-2-snovitoll@gmail.com> References: <20250717142732.292822-1-snovitoll@gmail.com> <20250717142732.292822-2-snovitoll@gmail.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: wkg64x5iixfq3pbzch9kz545kyhdiipo X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 6164F80007 X-Rspam-User: X-HE-Tag: 1752790250-878342 X-HE-Meta: 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 DVBJGonm tJPTz5j7pv1WBVdUCH/kYFFtQ42P90PYMyph1LbxOddu8QkikPtsQ0/EutaatSZUHcXlK+GxFV+FpdBjoWJYCkD+UQNHFyOC85kXAfc5xdzh1N543iF8voFzQlU6UCDeZtjpZxDuRonLwM5bTfw9/OpswzcwoYopYicyUiIPY7+F2jVqiaJIkX+Q7d7lXe/AZKS2nXCyxFcJl+ied3k8hO9baYPn1X0ZnaUQK3QijX0SZMyPFlFRUs4naYL+SmvWV3hEL/zWciOETHC7ogXCdrEZtnOZv6jUy73zAmPhOKXvNDj9ZRqtSmE1giCwk6q+2zEiILNK1bMaIbcH/iJUfIeUBTsUGcbphxitbjJTk4omZ7FM4CLNbUVSPuV3Suqv0PQJylX5WVBASEaw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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?