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Sun, 15 Mar 2020 08:54:07 +0000 Subject: Re: [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE To: Wei Yang , "Huang, Ying" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Hansen , David Hildenbrand , Mel Gorman , Vlastimil Babka , Zi Yan , Michal Hocko , Peter Zijlstra , Minchan Kim , Johannes Weiner , Hugh Dickins References: <20200228033819.3857058-1-ying.huang@intel.com> <20200228033819.3857058-3-ying.huang@intel.com> <20200315081854.rcqlmfckeqrh7fbt@master> From: =?UTF-8?Q?Mika_Penttil=c3=a4?= Message-ID: <92d4b0fe-f592-8da6-0282-2ea8a015b247@nextfour.com> Date: Sun, 15 Mar 2020 10:54:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 In-Reply-To: <20200315081854.rcqlmfckeqrh7fbt@master> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: HE1PR0902CA0028.eurprd09.prod.outlook.com (2603:10a6:7:15::17) To VI1PR03MB3775.eurprd03.prod.outlook.com (2603:10a6:803:2b::27) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.1.121] (91.145.109.188) by HE1PR0902CA0028.eurprd09.prod.outlook.com (2603:10a6:7:15::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2814.21 via Frontend Transport; Sun, 15 Mar 2020 08:54:05 +0000 X-Originating-IP: [91.145.109.188] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 71d31372-3099-4b80-38d4-08d7c8be6b39 X-MS-TrafficTypeDiagnostic: VI1PR03MB3647: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:5797; X-Forefront-PRVS: 0343AC1D30 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10009020)(136003)(346002)(396003)(376002)(366004)(39830400003)(199004)(6486002)(110136005)(956004)(2616005)(316002)(54906003)(66946007)(16576012)(4326008)(16526019)(186003)(26005)(7416002)(508600001)(31686004)(2906002)(31696002)(66476007)(66556008)(86362001)(81156014)(8676002)(5660300002)(52116002)(81166006)(4744005)(8936002)(36756003)(84603001);DIR:OUT;SFP:1101;SCL:1;SRVR:VI1PR03MB3647;H:VI1PR03MB3775.eurprd03.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1; Received-SPF: None (protection.outlook.com: nextfour.com does not designate permitted sender hosts) X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-MS-Exchange-AntiSpam-MessageData: qGL7gZGZTkP/8fnLQWyDL7D3h3FIJVolMbKvUUH02zkxLlNU3xdX2VL9bktBvzfJFZMvaqhNbQp5sfGO9Tj19VKUNW8A/C5ftGSli4RHYE0lEQ+8mid2OIb9fUyAja14Yi2hdO2ZVTCdH8RBH1Rdxw== X-OriginatorOrg: nextfour.com X-MS-Exchange-CrossTenant-Network-Message-Id: 71d31372-3099-4b80-38d4-08d7c8be6b39 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Mar 2020 08:54:07.1024 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 972e95c2-9290-4a02-8705-4014700ea294 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: IzSedMFTWGk+Xxf3DwtEWhi0fgJleQAHt9Fer6t9EC6wzXfgm4oPSZZWHjLFQo7Cl9wXrrr85BCqOPQqSVVaE7ZAU77lIbv3LMGwTQKdPDg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR03MB3647 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 15.3.2020 10.18, Wei Yang wrote: > On Fri, Feb 28, 2020 at 11:38:18AM +0800, Huang, Ying wrote: >> From: Huang Ying >> >> Now !PageSwapBacked() is used as the flag for the pages freed lazily >> via MADV_FREE. This isn't obvious enough. So Dave suggested to add a >> new page flag for that to improve the code readability. > I am confused with the usage of PageSwapBacked(). > > Previously I thought this flag means the page is swapin, set in > swapin_readahead(). While I found page_add_new_anon_rmap() would set it too. > This means every anon page would carry this flag. Then what is this flag > means? > > But not all PageSwapBacked() pages are anon, like shmem. --Mika