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 1D2E4EB64DC for ; Fri, 14 Jul 2023 13:58:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7BAEA6B0078; Fri, 14 Jul 2023 09:58:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 76A9D6B007B; Fri, 14 Jul 2023 09:58:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5BD7A6B007D; Fri, 14 Jul 2023 09:58:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 4DBAA6B0078 for ; Fri, 14 Jul 2023 09:58:37 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 26EF21C8241 for ; Fri, 14 Jul 2023 13:58:37 +0000 (UTC) X-FDA: 81010372674.23.3C42284 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by imf24.hostedemail.com (Postfix) with ESMTP id 37B67180015 for ; Fri, 14 Jul 2023 13:58:31 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=HdJl7kMF; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); spf=pass (imf24.hostedemail.com: domain of fengwei.yin@intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1689343113; 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:dkim-signature; bh=EeJz92wLvKOCF0Mtid71Dgi9kkEa4Q9tY/O8SUwd/M4=; b=e24veaqeWa4hAk/0kB8UeLaiDifkjGXmU44fTBYhsK7rYdeuZXBC0Z/ptCqI6vqiIlxTuH hU05gDLso9QfhM1SHMNAdsXLhWEYSPKrZ+DzQzpFYPcaV/X5tnpXE69fbgWj3JbYjG9u8E OngXayJrm2XQ6wl6XHVEq7WMU/QD1XM= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1689343113; a=rsa-sha256; cv=fail; b=UdiTxaxqZhSobERtBLj7iQcHHWandZj1GEi1V2/ESR6W8nz10+B9OMT5qtUEMhQWOSquj2 vWdTlqvsKbt73eJzfJmCKwpa6kjq22vudAOZDQ8kEJMNdURRlDlCYjnMNJwNGK0H+wiPO+ l/sGsTLPC4zxs3gUpu95yo6huojDDUU= ARC-Authentication-Results: i=2; imf24.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=HdJl7kMF; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); spf=pass (imf24.hostedemail.com: domain of fengwei.yin@intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com; dmarc=pass (policy=none) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689343112; x=1720879112; h=message-id:date:subject:to:cc:references:from: in-reply-to:content-transfer-encoding:mime-version; bh=tzRObSvgrNUbBanXFBXYTzdRES3RmVzSZgIZuB9X9F8=; b=HdJl7kMFhKLjJODnjGH9KU0BRawFMILNilFYcFGGqfNuUO9qWeHoLI+k roxCvyQNr3BCq+sUM4Rgw53M8aLcMusj+dstwsH+fvcBaxIqrIUMWsT94 aqS+lsLx4NJytlpTikbR3gB07yeQLd5nIswlMWIAIYsb5KkHWGYDMy9Xs r4x20glCQUDSRuobdYULfR92Xgfrmwd8zacFA9BD8PhKk+FL/afCY+Sgx VMAqd2+q9D3qan8NdVFTMfKf4mTjWDYp23ysHzZC9BTGT8RSPgUbZDKYm N5ifBfSczomdjXvcOfNC0l0yBzaJDBa4uWS7umL5/1i2ZcmlQ7U/xPz3t w==; X-IronPort-AV: E=McAfee;i="6600,9927,10771"; a="345075464" X-IronPort-AV: E=Sophos;i="6.01,205,1684825200"; d="scan'208";a="345075464" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2023 06:58:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10771"; a="725714373" X-IronPort-AV: E=Sophos;i="6.01,205,1684825200"; d="scan'208";a="725714373" Received: from fmsmsx602.amr.corp.intel.com ([10.18.126.82]) by fmsmga007.fm.intel.com with ESMTP; 14 Jul 2023 06:58:30 -0700 Received: from fmsmsx602.amr.corp.intel.com (10.18.126.82) by fmsmsx602.amr.corp.intel.com (10.18.126.82) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Fri, 14 Jul 2023 06:58:29 -0700 Received: from fmsedg601.ED.cps.intel.com (10.1.192.135) by fmsmsx602.amr.corp.intel.com (10.18.126.82) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27 via Frontend Transport; Fri, 14 Jul 2023 06:58:29 -0700 Received: from NAM04-MW2-obe.outbound.protection.outlook.com (104.47.73.173) by edgegateway.intel.com (192.55.55.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.27; Fri, 14 Jul 2023 06:58:29 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=oNOaFOgQE75r2Rmy0SsTKYZJ+T+r1Fsn8L+4PksefRMFFjMyPTTOawtGCkCZc9NOD7O29WUYZBvAaGir/x1nzbmdzbJcRe4HIuRRJeUz23z4owQ3GmqWhiJhXdYpF9Z+aXbxAJfl0kxyO2DhoCyfuyWMKe6zSjSB/JtGlK2NaReVaoHadY/sHRjmkcMJMBgLsQSepke7acZjJEiKZSd6XjV+C5Fo73xPkIiPVkRn7hgziN2rEde/NdqCGEJxOqg/8wOTZ2IMDvOEWlQu4YqoGYRiCEqZFB4d7IEjE/fM15yaPocHMn43oQkmlejqg0hKxAL3lgYAltIOIMSjQ40LbA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=EeJz92wLvKOCF0Mtid71Dgi9kkEa4Q9tY/O8SUwd/M4=; b=EM5KVYWuGgH6veSa0/et+73TAdAlZSahV5v4Pc2ureEpScodq27l2IkIndOK4JIUbJN4Wj5MyTruHVS9dXeXEsSai0iqf7pPjRWb4EF/2isaZDcgS8+BPKNmuFuhu25UL/FREMe9cxgyR0h1Jzt5ufP3uVu9mHQj62ZNgSvbDtER+L5IbyrsRHO1ebyW0rirnGwCb/KdZ4/DuZ4k++Sd9+6yufRJ73weJgpAyk9H1g5BYqW22SLknzgCINA0fkiJR2Kyw+x/v+TXR8ZJm8gs9X5JLxc50PMrhSHcKjB+FTP3mrS/XjDx/7UBZZsMl82Id9Am0qsTCEufW5bhjl/Lrw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Received: from CO1PR11MB4820.namprd11.prod.outlook.com (2603:10b6:303:6f::8) by DS7PR11MB7808.namprd11.prod.outlook.com (2603:10b6:8:ee::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6588.27; Fri, 14 Jul 2023 13:58:27 +0000 Received: from CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::e6c7:a86d:68d6:f2f3]) by CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::e6c7:a86d:68d6:f2f3%5]) with mapi id 15.20.6588.027; Fri, 14 Jul 2023 13:58:27 +0000 Message-ID: <9bcc8014-f5ef-9021-3ffc-032e39c32249@intel.com> Date: Fri, 14 Jul 2023 21:58:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.13.0 Subject: Re: [RFC PATCH] madvise: make madvise_cold_or_pageout_pte_range() support large folio To: David Hildenbrand , Yu Zhao , Zi Yan CC: Minchan Kim , , , , , , , "Vishal Moola (Oracle)" References: <20230713150558.200545-1-fengwei.yin@intel.com> <8547495c-9051-faab-a47d-1962f2e0b1da@intel.com> <2cbf457e-389e-cd45-1262-879513a4cf41@intel.com> <36cfe140-5685-bea7-d267-4a61f21aeb79@redhat.com> Content-Language: en-US From: "Yin, Fengwei" In-Reply-To: <36cfe140-5685-bea7-d267-4a61f21aeb79@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SI1PR02CA0055.apcprd02.prod.outlook.com (2603:1096:4:1f5::16) To CO1PR11MB4820.namprd11.prod.outlook.com (2603:10b6:303:6f::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PR11MB4820:EE_|DS7PR11MB7808:EE_ X-MS-Office365-Filtering-Correlation-Id: 0d0819f3-2e61-45ef-22a2-08db84726609 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO1PR11MB4820.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(39860400002)(346002)(136003)(396003)(376002)(366004)(451199021)(31686004)(2906002)(41300700001)(110136005)(54906003)(478600001)(6486002)(6666004)(8676002)(8936002)(36756003)(7416002)(66946007)(66556008)(4326008)(66476007)(316002)(6512007)(82960400001)(83380400001)(38100700002)(31696002)(5660300002)(6506007)(186003)(2616005)(86362001)(53546011)(26005)(43740500002)(45980500001);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cDBCVGIvWk4yNmZaN0l2ZVVEbFg1N25NR2JrWDdMMUx2N3oyaDVNdVRrNGQr?= =?utf-8?B?QlVzS3JxSkNzTzFMdEh1VFhPaUtNdDNHa3Z3NkNMVHBHSGtBMGZ5dnhtWEtD?= =?utf-8?B?UlNjYzYvQjZ1Sk9XTFh6d0Y2WDJrZ1dTbUY3ZVV2VStWR0M1UmtVZ1NUYVVH?= =?utf-8?B?THRsZ2EyMUxFSU94YTNyYUhaaEZkakNUSUl6NGhoSnJrZkVrUTJVbm45cUFo?= =?utf-8?B?UmxURENnQmk1SncvWXh0N2NaaTVrNS94dm1PNnRDdFlnNzZFYzlXTThYbzds?= =?utf-8?B?VjdLRVlqakErSjAyN2xFaTZYYUZyUERzc05ka2pmTmhaR1Zkd3J1a0FWN0hS?= =?utf-8?B?Z1gvdzZKL2NpZk9iVE4rcGxKenBaZ2RIVWpDaWpiQ0VJN1FnVE0wSFplZHRY?= =?utf-8?B?bVZudWxSZHk4UE5mdGJ2amhYVzhZcmRWQVRXcjdPQmpxOHlWTG9KSENURmxk?= =?utf-8?B?cUhvUjA3cjEwY0VJbHZmMnAxMU5QYXVBU3FrQWluOUg4R0g0TU93Y1BOUWJX?= =?utf-8?B?bmhxdWI3RXlYd2Q5TVptVDdGa1g0OHB0RSs4Mml3V3prQ1REWmVoL0ZRS0VI?= =?utf-8?B?aWd2TE1Id3F4SFBnL1lwWURHTkFDZDd3Uk9qMCs4ZGRDSzBxRFc2bForcUtP?= =?utf-8?B?MU9HQ3FXYWw2TXBqZkpTTEd0bjhyNCtCeEk4cFRsTmJHRDV1RjBjazkwRHN5?= =?utf-8?B?VnFPOUNiOUl5YzRkQWVndEVLT1VqaWkwR0l4WFMwUndQeTRUdlgrVEtWTnI0?= =?utf-8?B?S252Y0dhcGd5cWlIcVNEL1ArTEVWRjVTYmc2cjU5cmIxWVZEWXdUVXQ4Slgr?= =?utf-8?B?b1BuL0dZNXBJZlY3ak84bkc5cHZJMVd3ajVXTVYwT2luQ3FiMWlqQVY1OWRu?= =?utf-8?B?UFV3SGg4QmVRQktUdVdkMkJnRVBvbkpZNW5UVzU3ZE5yblprN0VES3lsK2ZB?= =?utf-8?B?ajBEOEhYZC9YNGFjc1cvY1ZaK250MWI1enpVTXlJZ3RkSC9QbTlpNllFaWdP?= =?utf-8?B?cFhLR3ZZcFEvNDlWOEpQOVhjVFJpWG93SG0rSHFveWV0aVlFSjlXMTV5ZUZC?= =?utf-8?B?SnRYRU9oZnFZOU0ySlhrLzByQndYdGpsZ3A2YjBRVlNVTVhsU1RrVUdzOTR3?= =?utf-8?B?NTdxMHFpSVNaaGYzWHFFeCtpRXYvQ2YreW5odEZPeUNHVHdjOVQ3YzF0SXU3?= =?utf-8?B?aEQvYnVHN2VJM2NhU1VoV3EvUkJhODYvRzVIb280ckJsT3hrNVJLR3RSSkd2?= =?utf-8?B?TkxvSHNrbldFSGpiZkxieDZJdWxKYVZQbGRnSG5yZ3cyREtjUjBGdjBMb2xB?= =?utf-8?B?THJJaHp3NC82N0dKcFAyUHU2Qi9waWhWMFRBcTM1WUxaMGJ4Q25UVVJtUkcz?= =?utf-8?B?UXhpL2FYQ0FQQ2h1dHNEOGFLNkNlTTB1ZU0rWGtJYmt5OXFWUG1pckcwRzRu?= =?utf-8?B?SW9SMkErUTNTMmhleFMvcFl1bXRUajVaSGpIUzNPU2xqYXd3Skxpd3AzWTF2?= =?utf-8?B?RGdWMWlvZ3VISW03SWtXQkNOejVFNm45SWpFSGp1SmtGSDAySGlJVjBKSW0r?= =?utf-8?B?YTBIYWE3ZnpCczdBUFBIeVFpQnkxQ01HcmFia24wMDZXK0ZaVEVaV1k2M3ZM?= =?utf-8?B?SEZwSXYycUVqczJYK3h4bFY5K1dBQnlxRFYrZnBhK3RaU2dwV1JQRW1lZnFt?= =?utf-8?B?ZUNHbVU4NWpReFNHemI5cmxpQ2lBS0lEUlRXTEx2dm9TYXIvZS94bm5rVGxs?= =?utf-8?B?bk1ZT1ZBUG5lTnljZTdSWHRPRERZUkcxN3hFRE1Ed29ZMDZ0a01WdlV4WDJU?= =?utf-8?B?TDA2WlordlJTQ1FUUHF5K1RUY3pLVDN5SFl4R01HR1l1YUNwT2hFbkcvMVBl?= =?utf-8?B?VHc3TDU2cm9YQ0R1b09pWXhBZlBHTDEvWGl6ek1pUVF4SVN0Qkl0Q3Y5K1Vq?= =?utf-8?B?YytET21iamtMYVErNDlmaVpBanR5cjZlV2RRTGMrbTQwMVFmV3lDckdrMWtO?= =?utf-8?B?MnhibGJoS1lWelpCT3RZUUgvdG8vS3EyNUtEZTdvaUIzeUttUndKRUpqSmtr?= =?utf-8?B?SDJGSEhDZUcxSVQ4YzJUcXU4dXNWcCtaYXF1NTQ3SFNDS0hzc2taeVBHQ2ox?= =?utf-8?Q?a4B22qgIiuwDGXCe2pOyvFG1I?= X-MS-Exchange-CrossTenant-Network-Message-Id: 0d0819f3-2e61-45ef-22a2-08db84726609 X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4820.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Jul 2023 13:58:27.6894 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: aLyfpOLf4YiWqtF4xr+3lmhE99yRc7Rr8AkUc5ip7aF/cV5xxOZzR1WPLK886PdZLJqqy5eY/ArAhQWCTmrWnQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR11MB7808 X-OriginatorOrg: intel.com X-Stat-Signature: e9hzb7rm1pkd5bq9rdkakb1hy69zekho X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 37B67180015 X-Rspam-User: X-HE-Tag: 1689343111-760571 X-HE-Meta: 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 2Upfhfez S3voyU5ao9sse8+iCL37e/wruQAEeQZQbMHZCYfRKFofYiW+wpdumdCQRCIeUpe0rPmXpKWlboqVvIDwSJjul3xJ9oFT8BcP24RSgQdhQ7L+O4uwzijiysyvs/d4tESAPxJqPMA+obZiQcKpKqhWQdMIlTBzl2Eg+0BeTNC4FxCT9+HKmMF5tyBDEhKMxHpbMBIGTKTuDd1Kco4OUVWtRZtjpSGdeLxDK8ilGhqPkk+ZrX/Lt0hPKw6tHx0tkyuWW4enmuB8C1yDe++xRRCfkvDVgzSRkEibJ1/uGfdyRH0hByIBwNZhKISW+lbgqCqqXqxiJIYeFvJofitucjs8Mm5XDXp/Zl3lGd5k8e7y7qf1Xc6qj/oRbAErTcbaDBWV0i/UN7ZTzv6bcfMg= 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 7/14/2023 5:25 PM, David Hildenbrand wrote: > > (1) We're unmapping a single subpage, the compound_mapcount == 0 >     and the total_mapcount > 0. If the subpage mapcount is now 0, add it >     to the deferred split queue. > > (2) We're unmapping a complete folio (PMD mapping / compound), the >     compound_mapcount is 0 and the total_mapcount > 0. > >  (a) If total mapcount < folio_nr_pages, add it >      to the deferred split queue. > >  (b) If total mapcount >= folio_nr_pages , we have to scan all subpage >      mapcounts. If any subpage mapcount == 0, add it to the deferred >      split queue. > > > (b) is a bit nasty. It would happen when we fork() with a PMD-mapped THP, the parent splits the THP due to COW, and then our child unmaps or splits the PMD-mapped THP (unmap easily happening during exec()). Fortunately, we'd only scan once when unmapping the PMD. > > > Getting rid of the subpage mapcount usage in (1) would mean that we have to do exactly what we do in (2). But then we'd need to ha handle (2) (B) differently as well. > > So, for 2 (b) we would either need some other heuristic, or we add it to the deferred split queue more frequently and let that one detect using an rmap walk "well, every subpage is still mapped, let's abort the split". Or another option for 2 (b): don't add it to deferred split queue. We know the folio in deferred list is mainly scanned when system needs to reclaim memory. Maybe it's better to let page reclaim choose the large folio here because page reclaiming will call folio_referenced() which does rmap_walk()->pvmw(). And we can reuse rmap_walk() in folio_referenced() to detect whether there are pages of folio are not mapped. If it's the case, we can split it then. Comparing to deferred list, the advantage is that folio_referenced() doesn't unmap page. While in deferred list, we need to add extra rmap_walk() to check whether there is page not mapped. Just a thought. I could miss something here. Thanks. Regards Yin, Fengwei