From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F4B53AD522; Mon, 22 Jun 2026 12:56:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782132997; cv=none; b=WSuP01vCGnrojUiQ5RA2C6WhkkWVMRplRJnS/QQrsOKthl/l3twkVmlbu2KTuMJQE3lrZ1MmjfFm3KfwSpohZmfMhLcz7lh2i/rJrV31pmaXvDs1PvLskEGoTgGpN685tFp3+vP6pyTn0D3D4QuXZ2UmWhBc9T90PwUVNX24Yl4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782132997; c=relaxed/simple; bh=l2iDIuaF1VKCPijPKmXFMyUN8rIqLYAfStTAg8/YV8I=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZHKrw3Nhn52bdfoNiJNHUDNMR7jbr5WQF6PpZihzob4vIQgiKjGUIvhes5zikUAt9rfAAtMBxu4TYMQBmd7XVMrRTagGXTaM/i4YDuWx7ltxGromykrC4LF8qdbAaHY3itDG9xt9g2h6RWqXRTJcpxXiDivLuXS5eNqtgyJGbKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dhTXUQv3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dhTXUQv3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77C321F000E9; Mon, 22 Jun 2026 12:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782132995; bh=l2iDIuaF1VKCPijPKmXFMyUN8rIqLYAfStTAg8/YV8I=; h=Date:Subject:To:Cc:References:From:In-Reply-To; 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 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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" 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--