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 E3ED6EE49A0 for ; Wed, 23 Aug 2023 12:45:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3690690001D; Wed, 23 Aug 2023 08:45:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 318D38E0011; Wed, 23 Aug 2023 08:45:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1923F90001D; Wed, 23 Aug 2023 08:45:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 073DC8E0011 for ; Wed, 23 Aug 2023 08:45:46 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CBCB24064E for ; Wed, 23 Aug 2023 12:45:45 +0000 (UTC) X-FDA: 81155341050.12.705FD33 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by imf19.hostedemail.com (Postfix) with ESMTP id B72091A0011 for ; Wed, 23 Aug 2023 12:45:41 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=b9DWj2zV; dmarc=pass (policy=none) header.from=intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); spf=pass (imf19.hostedemail.com: domain of fengwei.yin@intel.com designates 134.134.136.65 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1692794742; 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=DuTJp/mC5jTeTDwsEM3OJ/SeWQyZH5u9Ra54oOOUy/o=; b=NrfYrKJFZzxyyudwJftJMf6REo7P3JSDUcxquv96Q4+ftlElLpvRrO8VFr205veOmacHhd ahLlLZHwyUafi3dVsT7z4h0rwbSNv8aJgR8MlyIbChQIpKW/KPB9ctRaZnOPztg5NqxXy0 gQv9jZ10tk9towmyPqlWjOiLWBnHizs= ARC-Authentication-Results: i=2; imf19.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=b9DWj2zV; dmarc=pass (policy=none) header.from=intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); spf=pass (imf19.hostedemail.com: domain of fengwei.yin@intel.com designates 134.134.136.65 as permitted sender) smtp.mailfrom=fengwei.yin@intel.com ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1692794742; a=rsa-sha256; cv=fail; b=0D8sl3W8CsI2KfI71sk0D2BkUyJ8atctoxSRImBf/ko+xBjglPqit0j31yBE5Gg+Vjzson SVX0Xq9Akyhr8FO1lKikALoD1WQnKNIh5BAi5Go5SpghXIbL/8XHDSVQUzLGjI34+xHPLp 4D0VD+knff7vdmItnwYexAuCAzCJCAM= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1692794741; x=1724330741; h=message-id:date:subject:to:cc:references:from: in-reply-to:content-transfer-encoding:mime-version; bh=hxyHmCMEOO6UeXNb7qlUEPrZcFCpRtnQXYXecKuCNFw=; b=b9DWj2zVkbspuRn+MOh3F1/1/8N7fxydxiABtEXcOvBrd18HGHSQq2Vi ZBhkoJpLZGoKuPVRay0VcKtQ1+9hw+3O/TuGPSv++0UOU9a21HfycH4t+ dYYNeexEkNu3kIKSCqswJ0MMjJTfjs95YwAuKR2NF7cKut4f8y2ScEgKs 7bACCbNaPlthcwIKrprjfF2wtYV2Gxhrnrc21TRA1/80WaPK/q9eZqTMM +XAsSwxD/GnjIEIwSwDP/bljyU0UkYXOqH51Mz6+ZVF7ah6JVmuhM06x+ ytKT/qx6R1mnz1v40OFPqaQeT87kAZNuxlpNyyTdBTborP3pnLkx04HGA w==; X-IronPort-AV: E=McAfee;i="6600,9927,10810"; a="377908492" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="377908492" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Aug 2023 05:45:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10810"; a="1067465679" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="1067465679" Received: from fmsmsx601.amr.corp.intel.com ([10.18.126.81]) by fmsmga005.fm.intel.com with ESMTP; 23 Aug 2023 05:45:39 -0700 Received: from fmsmsx610.amr.corp.intel.com (10.18.126.90) by fmsmsx601.amr.corp.intel.com (10.18.126.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Wed, 23 Aug 2023 05:45:38 -0700 Received: from fmsedg601.ED.cps.intel.com (10.1.192.135) by fmsmsx610.amr.corp.intel.com (10.18.126.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27 via Frontend Transport; Wed, 23 Aug 2023 05:45:38 -0700 Received: from NAM04-BN8-obe.outbound.protection.outlook.com (104.47.74.44) 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; Wed, 23 Aug 2023 05:45:38 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=m6MsH5IhAKbzRj+g64a/I8e46LBurw4ntjD9m1v4A5iB/mVlLL6zD3IzRuI4BbDEjMuMpGDoeBUlfM10pVSoCoCN5slxMtfNTwtOlZYaKdFwpV3fWSSYBq+0QuahyfQtaxM0DfjIRC3uFNskczmOVSU+veo/oN56Serqx/bDGjUi95jvyhx23HEUUeV7QAJhCgskXi5K9wXMlMfHmhK8esKymO9aiBpnIysowx+C6k8cNxdFmKTY2D01lEi0U/gl3ME+3WcCseQpyZC45EA4/lYw7kS2PmLdbgQzkput9Udiby5u2buA2UVYIrz2cah8l/KE4aiZG2U4lLimbmcUxg== 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=DuTJp/mC5jTeTDwsEM3OJ/SeWQyZH5u9Ra54oOOUy/o=; b=Ao7UJnHqyGmVQ0NOMO5qbwU2R82Z6sIuMmFIiqk/u60vKbZf9ytzLFxNxzceIw064ZFF/49AD9rcFTvd29cRS1hbR6crt5vtFrduTBadhPNJf935Qgphmfx4h0AU4fIyircXK+pWK2Ip6wirZKf+OvKO6nIErPVFfCgsbfKnnNWXFyjYSNlf2QN6pTf5XKYJaexjuaaZYLbr070P21ZDzVxAhr/ilGAeaAcf/4/jWynLUwlR9SpfpmAlAzYbSt+QjWwiAOMTTcAxU5/t/2egekvqQ6rYtohe8uU5xquWRJoYZY75wxJsZGI6noNlxMrv2GBDIhA5UyQfNcgpYtrhoQ== 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 DM6PR11MB4674.namprd11.prod.outlook.com (2603:10b6:5:2a0::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6699.25; Wed, 23 Aug 2023 12:45:36 +0000 Received: from CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::221b:d422:710b:c9e6]) by CO1PR11MB4820.namprd11.prod.outlook.com ([fe80::221b:d422:710b:c9e6%3]) with mapi id 15.20.6699.025; Wed, 23 Aug 2023 12:45:36 +0000 Message-ID: <8de1d4b0-69b1-43f1-8d63-d3c0079e4cf6@intel.com> Date: Wed, 23 Aug 2023 20:45:27 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 4/4] perf: Use folios for the aux ringbuffer & pagefault path To: Matthew Wilcox CC: , , , , , , , References: <20230821202016.2910321-1-willy@infradead.org> <20230821202016.2910321-5-willy@infradead.org> <05db7f07-2ac2-f4d5-54ea-b5f1633e8c0c@intel.com> Content-Language: en-US From: "Yin, Fengwei" In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SG2PR06CA0186.apcprd06.prod.outlook.com (2603:1096:4:1::18) To CO1PR11MB4820.namprd11.prod.outlook.com (2603:10b6:303:6f::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PR11MB4820:EE_|DM6PR11MB4674:EE_ X-MS-Office365-Filtering-Correlation-Id: 14812cc1-38e2-47a3-23f4-08dba3d6d909 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:(13230031)(396003)(366004)(136003)(346002)(39860400002)(376002)(186009)(451199024)(1800799009)(31686004)(66946007)(66556008)(66476007)(6666004)(8676002)(4326008)(8936002)(53546011)(6486002)(6506007)(26005)(2616005)(478600001)(41300700001)(316002)(6512007)(5660300002)(6916009)(83380400001)(2906002)(31696002)(36756003)(38100700002)(82960400001)(86362001)(45980500001)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?WE1XTVdXUXJ2amNCV3Vyd0R1N1J3QTJpc05ZR1JXMndVdkU3YUkvTk0yd0Iy?= =?utf-8?B?cGxubll6RnNlTjVEcGZMRGVJYUJKS09aOW5BVWtla1FuZ0YvSy9XV2E2M0RL?= =?utf-8?B?Q01MV0JkSjB5Z09MWkE2aThrTmxHbFBjYmgvVm1JUURkbU9SRU56TkVRRjdK?= =?utf-8?B?WWZRdnhndWdXbzQwZFg4Qk51dU1yZUxwSHdwcmhGdTAvZmpHVDBiM1BFaXBx?= =?utf-8?B?WlU5YlBhTndjU1o1RGhtdlNzbkViVDAzb3hEdDQvTGFheFBIWElXMW82VjRU?= =?utf-8?B?UmpTeGRJVlpNMk1wRFZ4ejBtVWpnQ0pXcFp1OVNoRWJ1dm5tWmNBUnpobU94?= =?utf-8?B?aU11OGhrNmU4NCtVWXBHRGl1WkREYXJOd3dsRjM0REVjbU1yYUZkczdoOVNj?= =?utf-8?B?MXRGZFRyTHRIajNuaGhIcFpWS1o4Ukx6dW1VNFZqR3NaZjgwTUxrZFpvOE5O?= =?utf-8?B?N1kyeWtBNnFlenFUaVd1bDlWc2FWR0U0OXp2YlYxTk1pcnlsY0xIcCtvUGw2?= =?utf-8?B?QWpuaFJaYVdxRkZGbmhhUVZKZ1IyTWVvRzVsNjRCOWpBMC9WYWRWMnJZd3lM?= =?utf-8?B?c3JrNVozOGMyaldiUldFdHZtWWtMNnc5SzBmVCtWSi81Rkd4OWNFOWVWMG4y?= =?utf-8?B?RDA3WStubitTVnk4WDBCeVJ2OENCdmxqZTdidTdDbkJXNFEyczZLaXBlN1Nq?= =?utf-8?B?b2VYc2I3d1dxNXpoRVdTWFY4ZzNsejVoYUtvSmVpOUxkT2xwbzNZOEVRa0FP?= =?utf-8?B?Q0h2Wk56MnRWT0Ivbk5SaHBVZ1ptMDk2Z0tUNlBnSFBOSlFjZ2xNL1NSQnly?= =?utf-8?B?Yy9mN2ViY1JWU2REZlI1dzBwVWNSRnRjWUI4ckJ3amtLMFE4WjJUMjJBUUEr?= =?utf-8?B?QXdlbXRlbGFHTktIL0plK2d4ejkvc2pPYVd1K1dNQTNPM21ibXJWUWkxdDhH?= =?utf-8?B?YW90OCtWblNPd1VrV2VaMUJ4QnBadHZnMnlaY2ZDdFJvMFZ6dXFVRndoY0pN?= =?utf-8?B?cUFsUjFsWUpkd3pRN3dVK1IxenE3b2RwVER5SDdUaDVGRVE4aC91aGdUK3Rp?= =?utf-8?B?VFBSaWJzZWdqM1FvajU3eUo1ZnBJNjlQM1dYMFpBbHJOTHJXQUdqMEZCT0Nz?= =?utf-8?B?eno1OG5jZDBsVlRXaXVkYmxRdmorbHk1QmdKWkFKcTVYOXgrZUNBcWt5bVVs?= =?utf-8?B?Qm1TNll3OVRhTFdXUmFrdk96dzIwUWxHRFNrMm4weU9NM3grRUdORkFnNXcv?= =?utf-8?B?M0NyQ0JVbTd0b1VoWTh1RExOK2tXdnp1ODljRTBxZGJSRW5OeUdDR2JpWWFH?= =?utf-8?B?SDJTOWJzTmt6UTZmdGdDMlhLTEpXZkNWZnRBMmRuNFRHRUFHcGI2UjlxK3NP?= =?utf-8?B?b2dvM2h6Rmc2VFBHOFVPVTlDWGVmMFYwTWZ3S1JMUkpwOVNCK3JYcmVPd3V0?= =?utf-8?B?Vy92VHh1ckV3TVAzWlRhUmVLcisxcWNjakZFV09HMFNLUUY3cjV0RW5qOG9I?= =?utf-8?B?cHFnaWtzK212aHU4OTZycjJDZm1sZ2d5VzMxc1pkcWdBUnl0cVRzOVJEaUhn?= =?utf-8?B?UDIxVlo2UStJUFhqUG9ETEhXOEtCdHV2SE1VclBQTGlJTlBwcFdva1RkRFFX?= =?utf-8?B?b3YyUlJGSkFmY3I5VGFaQmhsbWMrWjhKM1BGazNOd1FlbVdMeFUrWVQ3Zy84?= =?utf-8?B?eTZORzBRcnVOdjhvVUNhMUttd0FaeGpNQWw1cjgzZ0pHcTR4RllReHJPdFlU?= =?utf-8?B?WHNTeUdiWEgxSElGUjJJclJQNXJXa01iZStBVGFUS2NIQUpXdzJqdkwxRnF2?= =?utf-8?B?Z0NNL3RJbUNrWlppRURFRGdQb3dSL21ud1hVUWprQWZCSXM2NFA0Vk5MSnhy?= =?utf-8?B?V1dNdjRoNC9HZitEKzNsN0ZNbS8zdFVFRnFTWm9vdEp6Z1pSZUE1VzlRUXlL?= =?utf-8?B?aDYyd3pBVDQyb0RsWkwrZWdCcEh3NVNtTVRLbXR1T2tMZ1JONVN0WllheTli?= =?utf-8?B?bUcxWW5pcW9UVGgyaUJ5Q3dRcmJBTUFWSDZGS1V0K0hIbjdHU3FFNVhVV0ps?= =?utf-8?B?WlNRdnk3Y1pKQ0VMS2NBUENHZmY4dVAzVEZwWTUxajJWS1hJZ0lKRzMrNmdy?= =?utf-8?Q?+1F6a5EuLJH5yWqAGVdUiU3xS?= X-MS-Exchange-CrossTenant-Network-Message-Id: 14812cc1-38e2-47a3-23f4-08dba3d6d909 X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4820.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Aug 2023 12:45:36.4142 (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: nMCHVsFN6EDwi8H7IsduT8vw54BSmFLewzxedk6Q+v42F7M9LolULpoCW9BmJ4j0Hp3NWMW/dMDy4qGJzzlPLw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR11MB4674 X-OriginatorOrg: intel.com X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B72091A0011 X-Stat-Signature: gp7h8q9itfxja3hniezq1nudb75axmhn X-Rspam-User: X-HE-Tag: 1692794741-942215 X-HE-Meta: U2FsdGVkX199lBl7IGsOeJ+PRmj5YG7KCy1WzFLWBjHG4rw7EpRn9nH3X4F2KBezc1IGOTWOZKBaPhV7gplxulCUcMGAQTZ5FhkrK80ASrdV2a9r/xrzYyI/Ue6jPZ0PZDClnNI7BwmPWt+AnDBTKb5WNM54m48RDX9lkHr6X4rYHTX3ppYQX3gTKq92mrC1JQxh97JuG1a+OE55lOy7826c55BEkvA7fa64MNSK5Bo6Y8KGE3e8JZOxsIA/LKU48imMmhUSeezCGJphcB1zXlLwyjjSkpzFPHInbdT99SVv9DRw4OnGb/u4LoqwoknClWwUtbLbU314aKfVvXRBSZh9S3n/NikqRWNoIZeFYvBqemeRS+LuSO61IPo36OCAToWvX8QSWph6+dIj50bjrI//JZRSPfOlo37fFI8/+lKsNU1fP815AV5vxM/5L2b/zTvQUvWqTmjgR27nQsiEy1rK8O4RtE5RWoxC6yX8ninZ6YZUYHtNI5yJ4/QNI9NXfKWpW1U1upm5V+qODqdeNmppchoUaNVSxYj1XJQqRlIYiNDyQSiBXDqsXE4GovfGcjfAVaiNdoYZBxFpLHcQqSQg9+/MRwvQd93n+ONkH7GVGBUYLsoS2N1VqR1pYszOF45snrq8YKOBDJoke7W2qyJ8zp9VZht/fDE3DlBd9Cy8XjiqhNlnfcdwqmKdYgF89KQBhKOei4GrKrMqHqChp9zDcRH7B//38smzods5tQksbL0Z8/raJ+4sxe5l33hk3u+xijH/krZ1Ghl74nh0b/TGmHXzDOI1EoaBbl+pVvXq5UwoG2xdnPTSc7BGn8NcaKRyaNZER8MFf2rBfO8l/jzQZc97WS74jw11t/SvR2jUislR61k8t0smuc2U7W2JjjLbSKpOhxOcBnMTC05kqyy9xk/+Olu72GSMt07xnVgvbteUc+CdLprhmmf/N5skqQLwwdW2rd15obFSARM iVhW+HET HN3bpHqOYZc62vSvZzAUWbV+x2qRDIRqFut+iCCs5V8qt/IUb0MVnYxvhOOYYOp1dyhz09Givz7EwUR4TqPni4CbUBHhnDE4xvHp7bMv8MNUhcON7JBPP86wnJnZqweU0JF7Tewao0Zu+F7jiPHpnEokTKwvU4hSaI+Az4WFsLh06DyYOxt+diJleowvSU3JMKvxYXvcqqWI5+uTFNBpGlVzqcL9uPfxI1RFMdvgejvAhqIm/RNHOFR4L+SiN7LhgVywAs3TNapaRIqyczsr1McB9R5sqCV3VUVCtKw3DOPN6BW5HasLa2HfeMpItQ7yWw2gm 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 8/23/2023 8:23 PM, Matthew Wilcox wrote: > On Wed, Aug 23, 2023 at 03:38:13PM +0800, Yin Fengwei wrote: >> On 8/22/23 04:20, Matthew Wilcox (Oracle) wrote: >>> - get_page(vmf->page); >>> - vmf->page->mapping = vmf->vma->vm_file->f_mapping; >>> - vmf->page->index = vmf->pgoff; >>> + folio_get(folio); >>> + rcu_read_unlock(); >>> + folio_lock(folio); >>> + if (!folio->mapping) >>> + folio->mapping = vmf->vma->vm_file->f_mapping; >>> >>> - ret = 0; >>> + return VM_FAULT_LOCKED; >> In __do_fault(): >> >> if (unlikely(!(ret & VM_FAULT_LOCKED))) >> lock_page(vmf->page); >> else >> VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); >> >> As we lock folio, not sure whether !PageLocked(vmf->page) can be true >> here. My understanding is yes if vmf->pgoff belongs to tail pages. Did >> I can miss something here? > > There's only one lock bit per folio; there's no lock bit for individual > pages. When we check PageLocked() on a tail page, it redirects to the > head page. > > __PAGEFLAG(Locked, locked, PF_NO_TAIL) > > #define PF_NO_TAIL(page, enforce) ({ \ > VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ > PF_POISONED_CHECK(compound_head(page)); }) > > #define TESTPAGEFLAG(uname, lname, policy) \ > static __always_inline int Page##uname(struct page *page) \ > { return test_bit(PG_##lname, &policy(page, 0)->flags); } > > and that expands out to: > > static __always_inline int PageLocked(struct page *page) > { return test_bit(PG_##locked, &compound_head(page)->flags); } > Ah. Here is the trick. Thanks a lot for detail explanation. Regards Yin, Fengwei