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b=Qyml6Vna2GlmWkaHpV2CzqTk/TiBPjZFisqocFlAqeSVjcfs9QIL2KzoA2KrY5pth b7MhxxY7U5YhZNnxStCjrINja9Rv8OsCLHAjxZEYv5tOw0bmp30+g9oKjw02QZIG+6 mkHMJpbEAVYH3laODVT6tYnMxROLMQDMQ252ByfrlVf/HnMeJqzvTO9vXw7TDhY9bn rQo5KY91IqevgCelioj87QElpShoX32TVqKGe5FU68bOYlLZm/o2FzLy19YpqJWfaW OXGbe76phmRsRCy/t3kTfprp4UeQQd6ea5WaxuMFsTEZ2SdWulXiPZH852bB7Mj7KU Yu5AuBqGksktg== Date: Tue, 16 Sep 2025 22:23:54 +0100 From: Will Deacon To: Yeoreum Yun Cc: ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, corbet@lwn.net, catalin.marinas@arm.com, akpm@linux-foundation.org, scott@os.amperecomputing.com, jhubbard@nvidia.com, pankaj.gupta@amd.com, leitao@debian.org, kaleshsingh@google.com, maz@kernel.org, broonie@kernel.org, oliver.upton@linux.dev, james.morse@arm.com, ardb@kernel.org, hardevsinh.palaniya@siliconsignals.io, david@redhat.com, yang@os.amperecomputing.com, kasan-dev@googlegroups.com, workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH v7 1/2] kasan/hw-tags: introduce kasan.write_only option Message-ID: References: <20250903150020.1131840-1-yeoreum.yun@arm.com> <20250903150020.1131840-2-yeoreum.yun@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1C111C0010 X-Stat-Signature: mgo9uducu93k98tuphjkkm8itjriyn3s X-Rspam-User: X-HE-Tag: 1758057843-709808 X-HE-Meta: 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 RgiLiwQV fTlRwenrkyPHBq8Zq2+ZY+vlcYDfgE2ZhYlI0zBCed3B2caSwq9ccfgdEs0sazqwvmJ91dK2RpTvXealtEL0a1YSie4OgR1BU+y/91s7aL2Qcyq0JuwwV67YtWpAQm6oGUYXBMhjai3FC72Ol0emZ+xBMpM0CFaEv9NmQAsPBzGMJhxX3mfAITnWwatAx00ixDkcvo3IhTYQeWtFAK6TVMtTgx0n1dRIm84G5iWWba5Yht/yFgQEg4gNbBmxY+lp34ds5IF0yx3zDQKnAXTzr2BcDJt44rtjGk6ZJVz6GIMu6o2r8TbaF2xa5kUyfpOoZCHUchlgKoUAHj7/wr0YlwlKKwJgn+62sQKPbSncwtI+l9pUKFj7+joJswg== 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 Tue, Sep 16, 2025 at 09:19:30PM +0100, Yeoreum Yun wrote: > > On Wed, Sep 03, 2025 at 04:00:19PM +0100, Yeoreum Yun wrote: > > > + switch (kasan_arg_write_only) { > > > + case KASAN_ARG_WRITE_ONLY_DEFAULT: > > > + /* Default is specified by kasan_flag_write_only definition. */ > > > + break; > > > + case KASAN_ARG_WRITE_ONLY_OFF: > > > + kasan_flag_write_only = false; > > > + break; > > > + case KASAN_ARG_WRITE_ONLY_ON: > > > + kasan_flag_write_only = true; > > > + break; > > > + } > > > + > > > kasan_init_tags(); > > > > I'm probably missing something here, but why have 'enum > > kasan_arg_write_only' at all? What stops you from setting > > 'kasan_flag_write_only' directly from early_kasan_flag_write_only()? > > > > This all looks weirdly over-engineered, as though 'kasan_flag_write_only' > > is expected to be statically initialised to something other than 'false'. > > For the conherent pattern for other options. > Since other options manage arg value and internal state separately, > I just followed former ancestor. I'm not sure it's the best option to blindly follow the existing code here. To pick another kasan "mode" at random, 'kasan_flag_vmalloc' is initialised differently depending on CONFIG_KASAN_VMALLOC and so allowing for the default value to differ based on the kernel configuration makes sense. But that doesn't apply here. I'd recommend starting simple and just having the 'flag', especially as you already made a small mistake because of mixing up the 'flag' with the 'arg'. Will