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 A86F4C77B7C for ; Wed, 25 Jun 2025 06:06:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4BBCB6B009C; Wed, 25 Jun 2025 02:06:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 493AA6B00B3; Wed, 25 Jun 2025 02:06:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 333D86B00B4; Wed, 25 Jun 2025 02:06:02 -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 1D9506B009C for ; Wed, 25 Jun 2025 02:06:02 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id C43FC1618A9 for ; Wed, 25 Jun 2025 06:06:01 +0000 (UTC) X-FDA: 83592887322.17.E8972A8 Received: from PA4PR04CU001.outbound.protection.outlook.com (mail-francecentralazon11013013.outbound.protection.outlook.com [40.107.162.13]) by imf17.hostedemail.com (Postfix) with ESMTP id E513E40002 for ; Wed, 25 Jun 2025 06:05:57 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=arm.com header.s=selector1 header.b=ofeM6nMs; dkim=pass header.d=arm.com header.s=selector1 header.b=ofeM6nMs; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf17.hostedemail.com: domain of Dev.Jain@arm.com designates 40.107.162.13 as permitted sender) smtp.mailfrom=Dev.Jain@arm.com; arc=pass ("microsoft.com:s=arcselector10001:i=2") ARC-Seal: i=3; s=arc-20220608; d=hostedemail.com; t=1750831558; a=rsa-sha256; cv=pass; b=0k0ilD9J9OpPrcnh0jv7iZzLTZEi6rwnLI5ZnawL0qa/ez+CpoWv033dW4dVBEtYwNFOTR eVfKkLLSS1DGoOo53vfhjeTvoBHeyOLBuSTOPQvVm04Q1Q5rChnL27QNunFdXRdwxaILk4 9COLFJ2FNKM76aglCGCvo3zvcO5pWRo= ARC-Authentication-Results: i=3; imf17.hostedemail.com; dkim=pass header.d=arm.com header.s=selector1 header.b=ofeM6nMs; dkim=pass header.d=arm.com header.s=selector1 header.b=ofeM6nMs; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf17.hostedemail.com: domain of Dev.Jain@arm.com designates 40.107.162.13 as permitted sender) smtp.mailfrom=Dev.Jain@arm.com; arc=pass ("microsoft.com:s=arcselector10001:i=2") ARC-Message-Signature: i=3; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1750831558; 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=SPBMbC0oSRdI56ie9FeogRMMsTws8hQLyYP7wDeeQ8o=; b=PxFniD4Jq2Brxa/qMIKEP895t4Go49tM7/0wai/at7d+Nv2YuiPgGNGakclCrDU3fdze9b EgcF4Z49lsGKuQBk222GJjLE6GcKKwKjdMw3MV9dAtdrIVuEtpDGFfRMACfBfy0G3F9pEx fNas/o4kHIeqt5t3FUDrW1PrKCd/oLE= ARC-Seal: i=2; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=pass; b=vFaLeamZSWv5fMD+Rewj2JprzXfzVujlaOyf5nw0fqYdxM8opV1Hmvt8SR/Gc3DktzqwqoXkA0Tlj5IqzS3a7lWIcq4C2WRpe9Ka3nSjS7tgbzflLY8VK+5oEvwDgIDMNNhF2AlsyrUg6cIlCZOPiLIeEKnCvgFXS/VUvbpd0dSH/uMJjdoLjR/DJDu054ecH6vTjjCOjmkYvxb8RD2NqI1BcEZgQS36QA6e3UTzsfG7QlJr9jAaIg2MGh9H2sXIvBI8GEy9QBjVV0gMNZxpHNREtA3c20x9FkO+RRC1dhBXirISRXQRk62YmNEp6qLin7ZCMWSFZjqgD2O2TzNdog== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=SPBMbC0oSRdI56ie9FeogRMMsTws8hQLyYP7wDeeQ8o=; b=UlV/4y0SOgQijlCTkbydIPdD5xcYl9wpoFBD04qvOk+Oa8PV3qFnQWx/IVGgaO4EpcTB1P4SM/uw26g70f9QKGtMSIyLmq39Rq1JkRemXt2/00zb0P87A4C4Zs5FLi3Xhi9VED0N21ETJ0Ntc6LlejGIxsnWTceuzSWbX8+cl0HDa5HZkFTfRgkbKCB2qYhAeeMUgy5hpzalDMNcqK1Lt29b0YqD8h42ed0au3j1+QbRksWd66hbaAAy5D8Q+GyKdIrxTsixaODEia1RLmyEUPzu2nSc8UZR2CeB1KfL70I+UeC2eyLwyBhVPTWkagvYbrjfFl7K1cH//HWzJnHudg== ARC-Authentication-Results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 4.158.2.129) smtp.rcpttodomain=google.com smtp.mailfrom=arm.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=arm.com; dkim=pass (signature was verified) header.d=arm.com; arc=pass (0 oda=1 ltdi=1 spf=[1,1,smtp.mailfrom=arm.com] dkim=[1,1,header.d=arm.com] dmarc=[1,1,header.from=arm.com]) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=SPBMbC0oSRdI56ie9FeogRMMsTws8hQLyYP7wDeeQ8o=; b=ofeM6nMsj0VYmmqnjC2zNjmv12g6pggEOSRgodZThAS32cQcmaya4wuk1bijCvWyJBcehFXTpleTMKzodiggbFiiidUd+6dFxfodDes+HElwbzI1Dc2g8V7czSfayxFpvtCcA6HnzExgxyl+ccZprKkq02/tSB+HxkhWWeoS1Fs= Received: from DU6P191CA0013.EURP191.PROD.OUTLOOK.COM (2603:10a6:10:540::24) by PAXPR08MB6640.eurprd08.prod.outlook.com (2603:10a6:102:dd::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8857.30; Wed, 25 Jun 2025 06:05:52 +0000 Received: from DB5PEPF00014B93.eurprd02.prod.outlook.com (2603:10a6:10:540:cafe::b0) by DU6P191CA0013.outlook.office365.com (2603:10a6:10:540::24) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8880.17 via Frontend Transport; Wed, 25 Jun 2025 06:05:52 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 4.158.2.129) smtp.mailfrom=arm.com; dkim=pass (signature was verified) header.d=arm.com;dmarc=pass action=none header.from=arm.com; Received-SPF: Pass (protection.outlook.com: domain of arm.com designates 4.158.2.129 as permitted sender) receiver=protection.outlook.com; client-ip=4.158.2.129; helo=outbound-uk1.az.dlp.m.darktrace.com; pr=C Received: from outbound-uk1.az.dlp.m.darktrace.com (4.158.2.129) by DB5PEPF00014B93.mail.protection.outlook.com (10.167.8.231) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8880.14 via Frontend Transport; Wed, 25 Jun 2025 06:05:50 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=A112Jg6iFhQleGhjd4fUlHOFcZ0r8fbuL1Bao74+cqJ1XFdSkkA6+llGxmlbtX5wUjaQ+Vb6wXcKaOToq6R2M8EWVZYnTidCXEgax2EIBg0UJwa1pDtiy5LWtEdbPMlM0Er2RPYE9ZEFs8OddFZ/e94vkDxfzkaX2Wp0UlSPFw4AKu/+FaZ73fnz/QsyL0Qb04vU1Q3SjhybJp94HnJlV/EK71r0H1dS5YinC0lWWjgHrQKg1AQLLkViv/kgCRyD6zDjR4jYfMB0h29wyKPfBBz6BsLBUtFSXnCOSOuLqn0105Wvt00avtbWEs5M+xn9w5KVdarJeftU/IrYnm6WBw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=SPBMbC0oSRdI56ie9FeogRMMsTws8hQLyYP7wDeeQ8o=; b=vZPZM/DEPPRJsxzRwZj6gkn0vtubUVc6ugX4YqrkAevTF2pKxCqlxT5e73MzgeoBhL0E/NOUfDuv6gBV/lt96/PXLmG5iPJ4e+CFi7O3Zq0ian2KS0yCioxIDmUOZ5jzIRKw/UDM2ntpegReMqWeSYM4UTEkWuBT0tBiSd8Ke5DvRQeMeW3XzYYi9XZgnoRAlEbWJt6mUMoxgB1mfBxuKD45aqZys7gi3FHNYTiHMYXQfl5ZcxYDTEUG2HK3br0VO2bmMZTYMz/+cU8s8CyD2h4xVbi2Nw1H1g4bRFhiqDEjhk8UkvBXX9QkHbZF9EJ6G08mDLIYMdOpeXFoA25XXw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=SPBMbC0oSRdI56ie9FeogRMMsTws8hQLyYP7wDeeQ8o=; b=ofeM6nMsj0VYmmqnjC2zNjmv12g6pggEOSRgodZThAS32cQcmaya4wuk1bijCvWyJBcehFXTpleTMKzodiggbFiiidUd+6dFxfodDes+HElwbzI1Dc2g8V7czSfayxFpvtCcA6HnzExgxyl+ccZprKkq02/tSB+HxkhWWeoS1Fs= Authentication-Results-Original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; Received: from AM9PR08MB7120.eurprd08.prod.outlook.com (2603:10a6:20b:3dc::22) by GV2PR08MB9158.eurprd08.prod.outlook.com (2603:10a6:150:d2::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8857.27; Wed, 25 Jun 2025 06:05:14 +0000 Received: from AM9PR08MB7120.eurprd08.prod.outlook.com ([fe80::2933:29aa:2693:d12e]) by AM9PR08MB7120.eurprd08.prod.outlook.com ([fe80::2933:29aa:2693:d12e%4]) with mapi id 15.20.8857.026; Wed, 25 Jun 2025 06:05:14 +0000 Message-ID: <8981f5a6-670d-4d01-8eca-d18fd285add8@arm.com> Date: Wed, 25 Jun 2025 11:35:08 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/2] fix MADV_COLLAPSE issue if THP settings are disabled To: Hugh Dickins , Baolin Wang Cc: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, zokeefe@google.com, shy828301@gmail.com, usamaarif642@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <75c02dbf-4189-958d-515e-fa80bb2187fc@google.com> Content-Language: en-US From: Dev Jain In-Reply-To: <75c02dbf-4189-958d-515e-fa80bb2187fc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MAXP287CA0016.INDP287.PROD.OUTLOOK.COM (2603:1096:a00:49::34) To AM9PR08MB7120.eurprd08.prod.outlook.com (2603:10a6:20b:3dc::22) MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: AM9PR08MB7120:EE_|GV2PR08MB9158:EE_|DB5PEPF00014B93:EE_|PAXPR08MB6640:EE_ X-MS-Office365-Filtering-Correlation-Id: 539e7a3b-f2c2-4a2f-5823-08ddb3ae5625 x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0;ARA:13230040|376014|7416014|366016|1800799024; X-Microsoft-Antispam-Message-Info-Original: =?utf-8?B?WjIyWlJGd0RWTUt5YW02OHJSaFN3d2diWFBoWmpHYjEyamZackR2UlRGanlH?= =?utf-8?B?bXQ3YWpHakU2cHRQNGdpVTdMTEdleEJhS2RPcTBiQWVaTDRROExmL3NxdkVU?= =?utf-8?B?aW84YjdNQ1JNZE5CSWtKcWtIRk45alErbXVoOU81b3pxUmNHc1NMdVlLVDQv?= =?utf-8?B?OFpINlY3dU8xU0hBWGgyWm1qcWhlZWUvNk9GZ1dYSS9KL2xzRk9JTGg3cmFr?= =?utf-8?B?Y3JBcnVxR3A0aGJhd0F3bnFLNVREK2dPSFRYd1hTb3BlclNQcnExTXNzeVVG?= =?utf-8?B?cHZnNGVKTEZ0bWd1U1ZTOGZuN09kVi9tSXJCNXMxZHRqU3dsREhMK3NIeEFH?= =?utf-8?B?dWpIRDBCL3FQbXNCSm1XUjFxZU0zeUNZUFh4ZkVPOWhBLyt3YkpNdktNcVhF?= =?utf-8?B?WDArWi9Pa01qVTFXTFFoaytOT2VXNW9JN0dxajFFNGZmTkViQ0xObUZFMG0w?= =?utf-8?B?bnhxTmpESVJkWUVCNDhWaklXbXlVNUhGSmNsZlZoVDVGdnlXUnhPRUNUL1hW?= =?utf-8?B?UktWMWJhWHBxQ051YkFpVmVZSitzZTYwNmpEODJYWHRvNXNXR2N3ZTh2TmVt?= =?utf-8?B?NUI2MUV0SDAyblYrVXQ4WUphTnIwVmJIbXM3Y3lyc0hTV1VZNnNPYlFKRjZx?= =?utf-8?B?Wk9wL2JxMENieUY4RDRIc2FZd0RNN1MvdENIZTl3VEZwK0YxUVdPNFpQWFhU?= =?utf-8?B?SUdpVGpLeW93Ly93Nm1YWFNYZDltNGNLVTBPeEJHN3JWZEs3UHE5b1RBZlFo?= =?utf-8?B?Y0pJbjBkZElpL1VGUnZLajhBZUh6TkU0OEsrTldtcTArTkdEcWJTeVNwWVN1?= =?utf-8?B?eVJjcUdINEl1QnJaOGl3S21oMjIwNWFDVzlOcE5QdWhObU84TWdYR044aWJ6?= =?utf-8?B?UVplQ255Uk1HQkFzYUJKQWdubVZFTEo5YnR0cGFPZzc2K1BZV21PY1NUazRW?= =?utf-8?B?Z1BCSjBURmtUOCs5NHlEdytHWGVpSWxTb2FOSUtzM3NMelRWNUJGOEhMWmlv?= =?utf-8?B?NThzeWxUOUJ3eVZ6NnFJN21kRkUxN1J0alRtRzZ3T2Q0WmpkN2ZKaXJ2N3kw?= =?utf-8?B?MFZTSGI5V3VGT3dwNENWL2RMM1c0NHFnU3FHSU1QdlB5MHZZcTJZcW03SDNS?= =?utf-8?B?azlUVVB4a3JwcUJJd3dFeVNPZmdhL05oOTFsSkhBcG9pZXhXYXMxL2RmempO?= =?utf-8?B?dGo4TnJWdUpnTWtPQUlBT1NUR0JPbER6bFJFRXRzeWRyZkZKT0ppY0lnWlQ5?= =?utf-8?B?RS9HTWRscEhvZytibVBqUzB2QXZycklCdDFDc0FQSDgwWmY5Y0x4ZkpVUnFY?= =?utf-8?B?Q0R3OGRWMjJVVVp1VWJ3UHpPRHlNNWRtZ0FXZGlsNWtvMEpIaHV6cWQzLzE0?= =?utf-8?B?TGZiYzRTSnRoY3h2Qm9xS1hLdW0wVlRsVG05VVlmSm1NYVB2KzNTUTRTRlBN?= =?utf-8?B?SS9WODc1bmF3ZGh0aGl2TmQrajJVRU5VckU2Y2RPbmtkcFZsWTE4MkJtbzda?= =?utf-8?B?ZFlXZ3BMQ0NiaDFZNU1peHIxbnNqeEpUNXpSamw3N1l6TkNYOGdrNTlSWDk1?= =?utf-8?B?M2pBN0xjN0tXUDFYRURUenJXQjE5aHNJNlprYVRYWDdEK2tVRVJLWmh6V3Uy?= =?utf-8?B?RkVGLzd6NW95cW9pVExIR0RBWjU2ODBrdnhXeUc1S00wQzVIYjhvcThyRHRR?= =?utf-8?B?ZVl3eWNsMFNsd2JyNnBtTlRoWUlGSUFJTnlOcEFObnBJUUdQNFVSU2d1a3Ja?= =?utf-8?B?Uk9lUUp1SnBjOFBUMER3c1ZMYXBMVjJtazVRZG4zMnJWS1hobUhrVDVGbDBW?= =?utf-8?B?U3NkTm84YndTc05lck55cmlHdmZsNnUyUnFvNlR4MC9ON0dmcldrSCszVnNX?= =?utf-8?B?cnRYM3FmK1BrM1ZuR0dNZm9IdkFiYlpOdkkzNmpOQTlyNmVSVkhRMnZVM2Z0?= =?utf-8?Q?qBwQ3XGjff4=3D?= X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:AM9PR08MB7120.eurprd08.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(366016)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-Transport-CrossTenantHeadersStamped: GV2PR08MB9158 X-EOPAttributedMessage: 0 X-MS-Exchange-Transport-CrossTenantHeadersStripped: DB5PEPF00014B93.eurprd02.prod.outlook.com X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id-Prvs: 0f5f28cd-280e-437e-2988-08ddb3ae4026 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|82310400026|1800799024|376014|7416014|35042699022|14060799003|13003099007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?SWkrS0NrN2dCcjlDYmpxc3Zic0taWDV6N05TT3JPY0ZQVnlQQUVXRGJ5WFJS?= =?utf-8?B?czZOVnFvUTN6dG5jNUw4d0tpcUtVQVYxUmRQazB4YVVmMFZvMFF6Yjhtb2ZU?= =?utf-8?B?b0ZLMXZ1b3BoK29VY3AyNDdWS0VuSWZGUnlZQytuMjJJQmV4cGgrRnhqVlFj?= =?utf-8?B?QXR4Z09CK0M5SkR0L1FLL0paRUd5bDRDT3BINUlaTVFhV3ZyV2c4djhPdDFZ?= =?utf-8?B?UVNlOTNBU3lyM09GbUIxRnk0ZjR5YnJ0NVlFRHJtWUVYZWlZSmZmdzVNNU5s?= =?utf-8?B?R29hY0x6V3dRN1IwMm9hMnQ4MFc0R1dIQTBubzFDYnB6bUtGSUtSU0tabkxa?= =?utf-8?B?V01TbEZUTGJsSmRCUjQ2VTdRR0ZabHp0MVhNbVNBdjJGWUoxYUxYWnJBcXpu?= =?utf-8?B?alV5TzExRDYzSXo5clc2dk5BeHRTTEJKYWprZ1RwV01tVXlyY0Z3SkpRMy80?= =?utf-8?B?eWtZQjllb0xBVnByMXFTWnFpUTFMaFd0T2JXdU9qdzlWb1I3TlBoT3VFSzkv?= =?utf-8?B?M29SRTdEN3RjRzg4cE1ka1lPelUxbEhYY0xqcDlnMklGc3RFQzhEQXZ4TDhk?= =?utf-8?B?Q3lCS3VVWVRjMzlnU2ltaTNhTlYxY3YxNnI0dmpITDFMS1ZnK2tQTU1uYTRM?= =?utf-8?B?RFdHNG9sUHFhYVBRRUFHREw0K3ZMNTljVW1GVXFEdWZMWW9tQk1tM2ZnNldv?= =?utf-8?B?Y0pZSlZDTFAwNDZ0Y04rZ3V2dFhTSmdSY3I2RnFvQzRLbTV1RFdQanZ4NFRr?= =?utf-8?B?anRhM2FTOFZOckNiQTIxRUpwQ0g2VnkrdXpQRWZoTkFjSVJoS0ZoVE1BVzdy?= =?utf-8?B?cGhMSms4QnV2M2gwOUQ1STlQdmxuNkZLeHlJY0V6dDFIaHdyckZrRCtUV1hG?= =?utf-8?B?ZTNzK2hGdmtNTkJpRlVTNzFNUnllNGVjOE9WbnBERjlxa2lCZ2xjUU5IQ0JC?= =?utf-8?B?T1BKVEwxcWlQaG9kR29TWFBGY1pHek00OWFWNDQ3ODY0N0RtQUhia0tMUk9B?= =?utf-8?B?VjlwNE5FcHlCYVdwS2NKK0VVQ2RiZGhDTjNQQWtCRyt2U0tRREFidjBjdE1Y?= =?utf-8?B?eVIzOU95cHBHZVg0WUdYcHhCTDREdGpZVUFtZWVtNy90R3hIMnBiTjYzaE4r?= =?utf-8?B?M25UQTNma0VxZ1pOeGVoY2gxZ3JRd3JGaFYwNU1hYUJ5dERFNWFxYTNLQ003?= =?utf-8?B?NjF1dnIrSVBIWHZYU29XRUpoVnc4YUNneFJ3R3U5b0pFcm5HQy8zVUwzaGJx?= =?utf-8?B?S08vSEdXeUNBcEZIdFVrUTMwaXRPaXQ3aWFudE4vKytOM3oxUG1LYUE2b0N3?= =?utf-8?B?emFiSmd1SFl1MDNlQktaSnJWcDVldXdQVTM3NTNGcHZtQjdzNGpVdmlkYWFY?= =?utf-8?B?elJpWjVFWGNhUlV2VWkzLzRhd01HUm8yaVY1T2NSYTd3RE9MQSt3OG1Mb2cv?= =?utf-8?B?MVBzWkNKdk9iWUlLL2lKM2lZeUxUeiswdFkwVHFYUlNVVGlhZTYyaHZFV3ox?= =?utf-8?B?YTlBTEZucVNUWHN6MC9CL0FKQTYzdHBlNWZFNXphblVGSVlpcnNiNWN5UlFw?= =?utf-8?B?NGNpdCt4WUYraEZHYThHRXkyMDlxSFdmaExEZm5vUG5SRlFJS0pGb2l6Witt?= =?utf-8?B?QVUyMjVvK1pPOTdDeE1CNE1XbmZHWWQ3RDZPODAzdHlvaGtHSk11bnFyeGNR?= =?utf-8?B?RHJlSWVaTjRzK3dkSGtpbDRsRVNic3V4M3RsL1hsRXpMT1Z0b2JCb2FaMjNF?= =?utf-8?B?dHE0aENFcWxKWUMrOTUzMWI5UFNySFRKSXRyWVlQM2lKT2lzZVpWOG9TWVJ3?= =?utf-8?B?OU02QkhIbjB1NHNENnl6N1FyV2N1NzNZaUNWSnk0N0hNTG9OMUtVQlFtSTBn?= =?utf-8?B?R25NNVZ2SStpb3Y5N3dZZjhLdEZOcmNMMlNFOEpxNiswbzF1dWw5aDdscmRo?= =?utf-8?B?SXlsaGNxcnU1OHdMb0drVHoyc2ZrMlppTFR6Y1VwNUxjNURqdzh5Q3YxeWRK?= =?utf-8?B?R2NSL255Y1FQL1ROTXBKQjFmTDlnbW9uQ1VIOTgzNWk3YXZiRExWMm9rb3Vt?= =?utf-8?B?TFZkSnlKcSszTm5VaDl2cEZXNnBVNEtKVXo3UT09?= X-Forefront-Antispam-Report: CIP:4.158.2.129;CTRY:GB;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:outbound-uk1.az.dlp.m.darktrace.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(82310400026)(1800799024)(376014)(7416014)(35042699022)(14060799003)(13003099007);DIR:OUT;SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jun 2025 06:05:50.6370 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 539e7a3b-f2c2-4a2f-5823-08ddb3ae5625 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: DB5PEPF00014B93.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAXPR08MB6640 X-Rspam-User: X-Stat-Signature: 3yarrj4istfaizz4m11gb3i3u9muha76 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E513E40002 X-HE-Tag: 1750831557-803297 X-HE-Meta: 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 yaWEG4Xc 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 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 25/06/25 11:23 am, Hugh Dickins wrote: > On Wed, 25 Jun 2025, Baolin Wang wrote: > >> When invoking thp_vma_allowable_orders(), if the TVA_ENFORCE_SYSFS flag is not >> specified, we will ignore the THP sysfs settings. Whilst it makes sense for the >> callers who do not specify this flag, it creates a odd and surprising situation >> where a sysadmin specifying 'never' for all THP sizes still observing THP pages >> being allocated and used on the system. And the MADV_COLLAPSE is an example of >> such a case, that means it will not set TVA_ENFORCE_SYSFS when calling >> thp_vma_allowable_orders(). >> >> As we discussed in the previous thread [1], the MADV_COLLAPSE will ignore >> the system-wide anon/shmem THP sysfs settings, which means that even though >> we have disabled the anon/shmem THP configuration, MADV_COLLAPSE will still >> attempt to collapse into a anon/shmem THP. This violates the rule we have >> agreed upon: never means never. >> >> For example, system administrators who disabled THP everywhere must indeed very >> much not want THP to be used for whatever reason - having individual programs >> being able to quietly override this is very surprising and likely to cause headaches >> for those who desire this not to happen on their systems. >> >> This patch set will address the MADV_COLLAPSE issue. >> >> Test >> ==== >> 1. Tested the mm selftests and found no regressions. >> 2. With toggling different Anon mTHP settings, the allocation and madvise collapse for >> anonymous pages work well. >> 3. With toggling different shmem mTHP settings, the allocation and madvise collapse for >> shmem work well. >> 4. Tested the large order allocation for tmpfs, and works as expected. >> >> [1] https://lore.kernel.org/all/1f00fdc3-a3a3-464b-8565-4c1b23d34f8d@linux.alibaba.com/ >> >> Changes from v3: >> - Collect reviewed tags. Thanks. >> - Update the commit message, per David. >> >> Changes from v2: >> - Update the commit message and cover letter, per Lorenzo. Thanks. >> - Simplify the logic in thp_vma_allowable_orders(), per Lorenzo and David. Thanks. >> >> Changes from v1: >> - Update the commit message, per Zi. >> - Add Zi's reviewed tag. Thanks. >> - Update the shmem logic. >> >> Baolin Wang (2): >> mm: huge_memory: disallow hugepages if the system-wide THP sysfs >> settings are disabled >> mm: shmem: disallow hugepages if the system-wide shmem THP sysfs >> settings are disabled >> >> include/linux/huge_mm.h | 51 ++++++++++++++++++------- >> mm/shmem.c | 6 +-- >> tools/testing/selftests/mm/khugepaged.c | 8 +--- >> 3 files changed, 43 insertions(+), 22 deletions(-) >> >> -- >> 2.43.5 > Sorry for chiming in so late, after so much effort: but I beg you, > please drop these. > > I did not want to get into a fight, and had been hoping a voice of > reason would come from others, before I got around to responding. > > And indeed Ryan understood correctly at the start; and he, Usama > and Barry, perhaps others I've missed, have raised appropriate > concerns but not prevailed. > > If we're sloganeering, I much prefer "never break userspace" to > "never means never", attractive though that over-simplification is. FWIW I had the same thought of "never break userspace" when I first saw the patch but then this point did not shine out in the discussion so I became nervous to mention it again :) > > Seldom has a feature been so thorougly documented as MADV_COLLAPSE, > in its 6.1 commits and in the "man 2 madvise" page: which are > explicit about MADV_COLLAPSE providing a way to get THPs where the > sysfs setting governing automatic behaviour does not insert them. > > We would all prefer a less messy world of THP tunables. I certainly > find plenty to dislike there too; and wish that a less assertive name > than "never" had been chosen originally for the default off position. > > But please don't break the accepted and documented behaviour of > MADV_COLLAPSE now. > > If you want to exclude all possibility of THPs, then please use the > prctl(PR_SET_THP_DISABLE); or shmem_enabled=deny (I think it was me > who insisted that be respected by MADV_COLLAPSE back then). > > Add a "deny" option to /sys/kernel/mm/transparent_hugepage/enabled > if you like. (But in these days of filesystem large folios, adding > new protections against them seems a few years late.) > > If Andrew decides that these patches should go in, then I'll have to > scrutinize them more carefully than I've done so far: but currently > I'm hoping to avoid that. > > Hugh