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b=dhTXUQv3s+G3948VNEUzwG8LXH8B99YNS4TcI8bDdEjy3NoNMQW8qC1bUUBSBq0Gl 9CS1dv+dU1cEQKaafkSSnUFEbNMHMoE6bXWDLVN7hboEaUaa0dWkHmM3ceKJRehheI 62XYgsevyO2fp8MahzfXuYboKooKO40EB5EXQNxnRy3bIhPev9AIkS9Bp6dEnSFUlM AjZ2wghBrD6limeBOmkB7AGjF4ZSY0kPfNw6svzcq0JIoX8gZWxztnmnWbaGHMOIDY oHJqQ4QcmtGnNGHxzYYAGiy5TkFXhUSIZiiK6+1TAFqEmqIuNPWL3IkLCH3FgkliFd sxlx9gq6SF69w== Message-ID: <4ab3bf02-70b9-4748-a12e-2bd564fec53d@kernel.org> Date: Mon, 22 Jun 2026 21:56:24 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/2] kasan: hw_tags: Add option to tag only at allocation time To: Catalin Marinas Cc: Dev Jain , ryabinin.a.a@gmail.com, akpm@linux-foundation.org, corbet@lwn.net, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, kaleshsingh@google.com, 21cnbao@gmail.com, david@kernel.org, will@kernel.org References: <20260612044425.763060-1-dev.jain@arm.com> <2a7d21fa-28c1-446c-97f5-2513f29157d3@kernel.org> Content-Language: en-US From: Harry Yoo In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------upsrUBOQYnFEnSXIs0AYK6aO" X-Rspam-User: X-Stat-Signature: yu97ibh9mbgm3ac1g38qx49oc84ig4gt X-Rspamd-Queue-Id: 9942618000C X-Rspamd-Server: rspam11 X-HE-Tag: 1782132996-265524 X-HE-Meta: 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 DVE7Lql3 HEJrTF0Tbb1DI//6BgR3wUt0//AIo7x+6gu9KS3074sC6NcvQUSWX4kbS4b91nUzfNXssw54Rm9+j/Pk3C3R/OjooxfnPATsdtbgea84/eGZuXWvryzVA7m3nTLUQjcnW+ktqRzwXtX9kDno8c6510MiRpvh+F5uUgLELxBE1pnFhyMXe5YKem9IBE7Cn214FABJwgpJDsFrHwfaQvFRjycKL+fWQojMOlFee0509zqRoJ6w/Wk2G7zsH3CX6fPe4m/Ru5AJnSsoYLyS0jsOTDt1sP26ZKKLETRRAYz0r2HzZL6KQ4BG17ux1Y9fzz5gzEVAO0BQHTWKCDciyNBQpelYvpHQaI1QqMmAB3xhPf3IIWX2PIm1jzNvtvR3+By2w/019o/lR4GQl5AKHc5jt+L4tC5b6AyitAGtwFZY+ZxdpGX6+M3ucG5M7YoECSLFK2bBGz9mj+RfFZhU4lDziWBoRAWXSjyKegcj8757jlcrPzG7EEvYh+YCHPvMKBclbom/8aAyhfxQje/KWG1jejGjXNOWCXVOyv/kaqErGmWaAwHbg6Kwjf4YXY1PeeJ+2BqYRMpOv5fCOjQc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------upsrUBOQYnFEnSXIs0AYK6aO Content-Type: multipart/mixed; boundary="------------Ps3zmfE9YngvIs8RaS9wbP7c"; protected-headers="v1" From: Harry Yoo To: Catalin Marinas Cc: Dev Jain , ryabinin.a.a@gmail.com, akpm@linux-foundation.org, corbet@lwn.net, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, kaleshsingh@google.com, 21cnbao@gmail.com, david@kernel.org, will@kernel.org Message-ID: <4ab3bf02-70b9-4748-a12e-2bd564fec53d@kernel.org> Subject: Re: [RFC PATCH 0/2] kasan: hw_tags: Add option to tag only at allocation time References: <20260612044425.763060-1-dev.jain@arm.com> <2a7d21fa-28c1-446c-97f5-2513f29157d3@kernel.org> In-Reply-To: --------------Ps3zmfE9YngvIs8RaS9wbP7c Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 6/19/26 10:04 PM, Catalin Marinas wrote: > On Thu, Jun 18, 2026 at 11:05:43PM +0900, Harry Yoo wrote: >> On 6/18/26 10:35 PM, Harry Yoo wrote: >>> On 6/12/26 1:44 PM, Dev Jain wrote: >>>> Introduce a boot option to tag only at allocation time of the object= s. This >>>> reduces KASAN MTE overhead, the tradeoff being reduced ability of >>>> catching bugs. >>> >>> I think most of overhead when enabling MTE comes from loading and >>> validing tags for every memory access (either in SYNC or ASYNC mode),= >>> rather than from storing tags. >> >> Is there any reason not to use STGM instead of STG + DC GVA when >> setting/clearing tags for large sizes when we know they are properly >> aligned? >=20 > STGM is intended for copying tags when paired with LDGM. Have you seen > hardware where STGM is faster than STG or DC GVA? No, I haven't. It was a question I had after learning that there are multiple ways to store tags ;) > For properly aligned > buffers, I'd expect DC GVA to behave at least on par with STGM. Thanks for answering! --=20 Cheers, Harry / Hyeonggon --------------Ps3zmfE9YngvIs8RaS9wbP7c-- --------------upsrUBOQYnFEnSXIs0AYK6aO Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCajkw+AAKCRCGXBN6rc5S 1qvyAPsF0DurImeEtMtFke9YXQWImsgXI+xfZ4SEz1mY+wbGswEA158qtw/Yf70R 7SKOnegedFGVqJzsq5p+vAkSpPMfJQw= =RsAK -----END PGP SIGNATURE----- --------------upsrUBOQYnFEnSXIs0AYK6aO--