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]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBB49C7EE2D for ; Fri, 19 May 2023 08:53:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 48A80900005; Fri, 19 May 2023 04:53:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 43A68900004; Fri, 19 May 2023 04:53:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3033C900005; Fri, 19 May 2023 04:53:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 208F4900004 for ; Fri, 19 May 2023 04:53:50 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id E078540A12 for ; Fri, 19 May 2023 08:53:49 +0000 (UTC) X-FDA: 80806391778.08.080366D Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf19.hostedemail.com (Postfix) with ESMTP id 421531A0013 for ; Fri, 19 May 2023 08:53:47 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684486427; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hyQLw11g+hGftGG4iCAG5rF7Yf0PyDNAVMXlYyl3FX4=; b=kZtlLhUsMTj5EmF/1KPeJHiIfGTPDYpcE1RP6XqOltxsUnZe2460UJFsTTjt0PDcx8d//7 kZjZtdvL06Qh80DMFbQnnnkZY8xExDCGb1Scx1k0BaDNt/FRFWj3kjhcZYBNK9cAHyVtp6 aGD0gU3zE8DYxgi+CJnYhjtqkTmohhU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684486427; a=rsa-sha256; cv=none; b=iT3jNECjxpS5m74KtS88/bUhQr1tQKUKwXQjQZHhvF+oZqq247zquxyd2ikTbepDBgESmB n7T1uZP8HKrd8ZeUJG3OqlXykbw4QHn4HZ8K/oDxBH16L8oRU1f8eKhPUpnGe8moaJ3Xki bji91IDdaO6tPFbLdbGaaitxqO+nnDk= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0451D1FB; Fri, 19 May 2023 01:54:31 -0700 (PDT) Received: from [10.57.73.191] (unknown [10.57.73.191]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EBC533F73F; Fri, 19 May 2023 01:53:43 -0700 (PDT) Message-ID: <2ee0f754-6959-4fa8-0020-06f2d7fc76e4@arm.com> Date: Fri, 19 May 2023 09:53:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v2 2/5] mm: damon must atomically clear young on ptes and pmds To: SeongJae Park Cc: Andrew Morton , Christoph Hellwig , "Matthew Wilcox (Oracle)" , "Kirill A. Shutemov" , Lorenzo Stoakes , Uladzislau Rezki , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev References: <20230518171323.83828-1-sj@kernel.org> From: Ryan Roberts In-Reply-To: <20230518171323.83828-1-sj@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: ceib7xotmqr6xg9u8nuunbx6jedkdm9f X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 421531A0013 X-Rspam-User: X-HE-Tag: 1684486427-214879 X-HE-Meta: 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 MBmxh5Kp BuZB3JIyZM/Yf2w/cNH3iAH5iNi/cl9LtFiy4q+AnqnbVG3V/FZIhoMZ6VjsHjhcCaXFIB6ankb5bV7puQTFCZUpKlFZJ2wfw3y7V/S/DUJUQt/j0Y8yOqL8P/cSsLEZpf3qXL2Foh8MG2mhxQX51lQqewAvPV10FbXw5G4od10oTgd5i8J5760W4j39qRKPEKNCum6Rxe/0PTHjjPeQyCCS6bJBKNn6CBh/4D9khQZM6ctLuXf4v2x12Fw== 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: On 18/05/2023 18:13, SeongJae Park wrote: > Hi Ryan, > > > Nit. For consistency of DAMON commits subjects, I'd prefer something like > "mm/damon/ops-common: atomically test and clear young on ptes and pmds". > > On Thu, 18 May 2023 12:07:24 +0100 Ryan Roberts wrote: > >> It is racy to non-atomically read a pte, then clear the young bit, then >> write it back as this could discard dirty information. Further, it is >> bad practice to directly set a pte entry within a table. Instead >> clearing young must go through the arch-provided helper, >> ptep_test_and_clear_young() to ensure it is modified atomically and to >> give the arch code visibility and allow it to check (and potentially >> modify) the operation. >> >> Fixes: 46c3a0accdc4 ("mm/damon/vaddr: separate commonly usable functions") > > Nit. The commit is only for refactoring. The original code camde from commit > 3f49584b262c ("mm/damon: implement primitives for the virtual memory address > spaces"). > >> Signed-off-by: Ryan Roberts >> Reviewed-by: Zi Yan > > Other than above nits, > > Reviewed-by: SeongJae Park Thanks for the reviews! I'll fix the nits you raised for v3. > > > Thanks, > SJ >