From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EA0D7D1A627 for ; Fri, 9 Jan 2026 13:43:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 60A9E6B0089; Fri, 9 Jan 2026 08:43:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B8526B008A; Fri, 9 Jan 2026 08:43:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4E5E16B008C; Fri, 9 Jan 2026 08:43:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 3E9576B0089 for ; Fri, 9 Jan 2026 08:43:37 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 04DCD1BE27 for ; Fri, 9 Jan 2026 13:43:36 +0000 (UTC) X-FDA: 84312542874.10.4EC8929 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf22.hostedemail.com (Postfix) with ESMTP id 49C39C0002 for ; Fri, 9 Jan 2026 13:43:35 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jq8+HDoW; spf=pass (imf22.hostedemail.com: domain of will@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=will@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1767966215; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FWIjlFv6jJqppx2LoyUbbHVPgKacvPuyCBOajXnJvKU=; b=lZAerN69bzupzcldWygKisruogGQMguKHwkeJwWoV/wrB4CohpB2mjUQJO52sfZFlWcFjN fyj0Mh+p0Fe7fEFhoPVE85aAK42MtvAT1nHXtyfqCvNOJIwYChLSvxeJRMVaA+B4hfqlb2 /0OerLPv+iufdRNI0K3kJaOO18UPwco= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jq8+HDoW; spf=pass (imf22.hostedemail.com: domain of will@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=will@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1767966215; a=rsa-sha256; cv=none; b=c5rDtT59qqrzxkP7syji+vD3ukD7KgzAUli4ZEMgP7L7ogBasg1KvhsRv+IYIB6wmdt+Ts xc4Qs+ftBBL1VCAt5CSkgrbMj/Ax3bbYFNqt85SdNlS95Qmnabn9IxNWQPLTeZ7VIRNJl5 wZvTmbbtiD1ypbr6Q/5R+jPNekMZGa4= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 4A75D40539; Fri, 9 Jan 2026 13:43:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A0C6C4CEF1; Fri, 9 Jan 2026 13:43:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767966214; bh=ijLJjYW1cc6SO67EopKRqCC5IeK0M9dJP6RDnaTpVqU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jq8+HDoWfq+dnQNCjupi8t3wJr3s2gFU/PZ+Mw9p2emhpnvQ4wtgBty04uXbNk61D pNNPamcF60pYnh283bb1GkqvMttXrjLp8u7mPUIvt9NWaV3fpMZbPRnkTuEPT0Llrj 8Yt3UjdNFby5p8HerssTXgGz6oX8DulSCX0Auw4wa5TWQHIbb7ZQlnH/wloeDJ6jtW yant4tlpZ7jRtbPwfiDiCLKl1YaqQ1cVNNNBicAEjsz+Qb/Tj7rv3d3L591HucBl9T j/jWJ/WBZe7w9ztoI5e6doC/wmtuASzCC/PVJHwCuzCs4X98ZeSZ/riOmzgPWfP7oR CwUWQShgEQbxg== Date: Fri, 9 Jan 2026 13:43:25 +0000 From: Will Deacon To: Maciej Wieczor-Retman Cc: Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Catalin Marinas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Samuel Holland , Maciej Wieczor-Retman , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH v7 02/15] kasan: arm64: x86: Make special tags arch specific Message-ID: References: <0db7ec3b1a813b4d9e3aa8648b3c212166a248b7.1765386422.git.m.wieczorretman@pm.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: ez8ja9iq6nf87hsz4rpu7fhku45yz6ei X-Rspam-User: X-Rspamd-Queue-Id: 49C39C0002 X-Rspamd-Server: rspam08 X-HE-Tag: 1767966215-626770 X-HE-Meta: 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 QyAJhHdp 46g3ukKjNwg3m59+ZpGdzkYshg5rvdRPTNyrOPyYBas+3TPRdzYaxzWppWXIVMy6uc70UnLM8pQH2sO0jBoXlv67/0LelKAg1S3ZKSQL+8yaYSXuW0LhBhU8jGJXcRs+Iufk4z17svv2Z+HSVq8RLEj/vXcCMfLS4TXf4NWlW+MqCa8tsg7BUGJdDA1CmR9OVMenpRmvlIbaH5VwDhjUMDPuCQHzZD1FAANObv3P/QYPrVYaBJMK8K5JYqserQldVCwbnI5FYM6OW2fhEY+w9gqqJfxiI631P5z/qcLRJo8TaCjRYPuQBwhS0FKTzVbUX1+Ve2hS5vbMJ4GiFnFgDyO4fbmHUXplT81RVD8qLhfgKHaBmxb+vn8rZaVb5/MPihKopOuYuV5zoY6j/GdqNoSoUbA== 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 Fri, Jan 09, 2026 at 01:37:49PM +0000, Maciej Wieczor-Retman wrote: > Hi, and thanks for looking at the patches! > > On 2026-01-08 at 17:56:39 +0000, Will Deacon wrote: > >On Wed, Dec 10, 2025 at 05:28:43PM +0000, Maciej Wieczor-Retman wrote: > >> From: Samuel Holland > ... > >> +#ifdef CONFIG_KASAN_HW_TAGS > >> +#define KASAN_TAG_MIN 0xF0 /* minimum value for random tags */ > >> +#define KASAN_TAG_WIDTH 4 > >> +#else > >> +#define KASAN_TAG_WIDTH 8 > >> +#endif > > > >Shouldn't this be 0 when KASAN is not in use at all? > > > >Will > > This file (as well as the x86 version) gets included in > include/linux/kasan-tags.h: > > #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) > #include > #endif > > #ifndef KASAN_TAG_WIDTH > #define KASAN_TAG_WIDTH 0 > #endif > > So the 8 or 4 value is only assigned if SW_TAGS or HW_TAGS are enabled. > Otherwise it's set to zero. Thanks for the explanation, I'd missed the conditional inclusion of the arch header. In which case, the arm64 side looks fine to me: Acked-by: Will Deacon Cheers, Will