From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A68B71D90C8; Tue, 10 Jun 2025 15:18:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.177.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749568685; cv=fail; b=BxEkvPKEjjJDwV349XSpVGYfh8KAd6uPxJeKiXKVCTIsAVRmAWX60SvCp0h6uA1ulkUenN4VDce5EiyvDVd8vL/1Qpi+PsUyYw0ZbMKZ75FhSzvvJeOlI0/orRWwbTBi/lV6LCh6erWveJ0A8KfuEtC0P0ZYGuATdLv4Is0eh5k= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749568685; c=relaxed/simple; bh=1RjTqebKKx4scLIqvhttyAlBOPmhlRIsM6/7kOhjrUE=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=eTPsyjQj5E8OtPKr1WPWS+JDNHNAjTHGSKPuXEdPeyJ8ZSvKv9CtS75iU0Jm8ft4V/Hd6sKNJ20wjjZuV5K0iqhKIO3NswC7Chr3lyNdfE6AtddByb5gZnZOmdVDSp7mAOhoXTMoH4WSK0KQsVQ2Y9+m0IZZb5nezuuM/Vki6lA= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=LXJ7BUlV; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=X9lSz3Gf; arc=fail smtp.client-ip=205.220.177.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="LXJ7BUlV"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="X9lSz3Gf" Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 55AEXeSF029113; Tue, 10 Jun 2025 15:17:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=corp-2025-04-25; bh=1RjTqebKKx4scLIqvh ttyAlBOPmhlRIsM6/7kOhjrUE=; b=LXJ7BUlVqhJlBW6p0ft15hxV1V5NraCDeM l2faSJH62ytuiUjqn1G7Foo7y6QZDG6QrnqWdV9p//sGYxpLVcRbPOcxC7843214 NXl8pOOMnB6HG0q6bFWwvVVg6QoVf9FhPq+Lfogq1/lKewR/nT5ek9wTAU4a5pyc +B6+bEx8+DkVeVlnvQHJxZYQIdLmyqgQUWYaqmt5dZ/kG6uwt5LCcZOSdN996pmq 97Wnq58NeJYz0c1LHVZYrhMYth8VFqobTLdWgH4Q9sfC7JCMU841sDOEcT5ywy0s tVSY1F9UybMOARq9TZD53qSmk5mnXpkKyV/edOtRWNz1TSVWtgOg== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 474d1v4gxn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Jun 2025 15:17:39 +0000 (GMT) Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 55ADf73W007539; Tue, 10 Jun 2025 15:17:38 GMT Received: from nam11-dm6-obe.outbound.protection.outlook.com (mail-dm6nam11on2081.outbound.protection.outlook.com [40.107.223.81]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 474bv8maq9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Jun 2025 15:17:38 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=NO1xWBsHcjv54bjxxCaUOEkukSRuaSydu7dHCI3ZXHVFNrG1W4lJ6S58lXA8+G8UIQ1xrAVRc/zAkXqTSsRGinXdu0ymMdmNPd9nTCuEOsHVkhV/3R+xH0O38ECvPdlEiedl7rpDrWAgiHFhPXL4hB2QhC0ATjVHNbGIX9I/kO63HfM79CUFoqkRysEzdeD2Ktsgw31vNZARUHQruGd3+5OhsFpLxvmVlITC5TSkJWOOC9JHQwfiufBR3qw2ubMLRxosyxop5RKER1iUUZ1KQHUrYRZbVcqG7ecd1uHwDdAx57x9ExeQy2jLJbCFFnV4OJuYvXVuhILP8Khp/aPvrw== 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=1RjTqebKKx4scLIqvhttyAlBOPmhlRIsM6/7kOhjrUE=; b=GuwqKbpaRZEVHtYZQ74FbxefAhmr5wesvgQLRkYUC3qjY0g65FcsHvWCzALq+V3pYVESVOhsPdJIZOyFZNhrCO9sh0/ONoJgzanjlY0EUuUeYRMV/xajr3eVLlDFDMO5NNeYi1h5/gXRQF/ceQPSOXcuE3cD5M+nWWUP1eL8gn9Tbcb9heCgux5hxcKB6fDYFUE5kB4oC0tKRoqWF4ucjRYlmcLjGqWRLucnvDm+2UIJ43/pFl3RTmziZsg4o5xgjvBV8G9Jf4cLGO2koyzKhu0MYfAcLhbCCrnRS2DbSGzY1NomMTZPkVEbY538rlRnY8NczgrlcGoEYcbVcn6K2A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=1RjTqebKKx4scLIqvhttyAlBOPmhlRIsM6/7kOhjrUE=; b=X9lSz3GfQ2zFpYZPttZGjljvtJYdqBlyWjFgfZiVykLSdtSJhikxCWRkchRTG9kgETnfr3mOyAaGGtwaVgxS6vMZVM1uPuHahcDiRhA+TZlbHkM4vB8ibr7ZWtwfdWGmgeibgb/m4MGD4uIsa0xqGlbUCdkEk+v30inXXx6eKU4= Received: from DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) by BL4PR10MB8231.namprd10.prod.outlook.com (2603:10b6:208:4e6::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8835.18; Tue, 10 Jun 2025 15:17:36 +0000 Received: from DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2]) by DM4PR10MB8218.namprd10.prod.outlook.com ([fe80::2650:55cf:2816:5f2%6]) with mapi id 15.20.8813.024; Tue, 10 Jun 2025 15:17:36 +0000 Date: Tue, 10 Jun 2025 16:17:33 +0100 From: Lorenzo Stoakes To: Usama Arif Cc: Andrew Morton , Shakeel Butt , "Liam R . Howlett" , David Hildenbrand , Vlastimil Babka , Jann Horn , Arnd Bergmann , Christian Brauner , SeongJae Park , Mike Rapoport , Johannes Weiner , Barry Song <21cnbao@gmail.com>, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Pedro Falcato Subject: Re: [DISCUSSION] proposed mctl() API Message-ID: References: <85778a76-7dc8-4ea8-8827-acb45f74ee05@lucifer.local> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: LNXP265CA0090.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:76::30) To DM4PR10MB8218.namprd10.prod.outlook.com (2603:10b6:8:1cc::16) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR10MB8218:EE_|BL4PR10MB8231:EE_ X-MS-Office365-Filtering-Correlation-Id: 9b300aa0-b387-4154-66f1-08dda831ee53 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?WMyMKC7OizxFBQ77lGWdqg3gvPc7V8daeFCtQZxCKs/OvpBkZRtImICi4hVF?= =?us-ascii?Q?apiXS2uwIAkoTPN1gSeRLtQD/EnyNrXClLKH4/iEakiravyZqnHk/JH+Zk1O?= =?us-ascii?Q?ueD9zhMAnLXvq/Vyj0IaHqeK0FQQ9fqiXJLlbpjF5OAdzWW/FZyD8HNKVuqM?= =?us-ascii?Q?1mYVFSOuYM7Hl5/zFAWhbiGF2QB6wga5T9OEJcXymEobaeCcaUL9KXSUf1p6?= =?us-ascii?Q?G3wtCYgCxq3STi1tim2z0OGrVGnYJMRLVuYTTWAyObJuRJWNCL7AO19x51O3?= =?us-ascii?Q?YaA2+U46GNhRpTxB2pYLr2/GtE1s/PwuJnuoZHD0TGpu4nZJ017AmEoht/Yo?= =?us-ascii?Q?aL4SEmX81tVawiPZgJWPSqaH95DFXyxmcmS83I1lkgCD98LHKi6IAnzxGY7Q?= =?us-ascii?Q?G/W9ZnWR7fdoJPTELEu56OA8O9QqBeNorkQ9L9IAobkeWiiHNk0eEF5HTX4I?= =?us-ascii?Q?ikhKw5wdPcWJal6IvycmxbuO4Ov75NtUXvpRRwKuRbR5QBI5QUbb7WUCTEMP?= =?us-ascii?Q?ZcuQH3obAVrjYfCPj946pdapm27YXLjbiWXkT5fdZIgev/aEYZfrldLijsVF?= =?us-ascii?Q?lGP10T7qpRZoRcwemHQJQpQT3XSPo7iKk8mjYa5/pxc7oI1lN6BtHefAQa91?= =?us-ascii?Q?4SHmF5Xpo+f0yrJhny7GIeaStWq8DA5tV34CfEzYK8hG1PI5881xtah+1SKt?= =?us-ascii?Q?/dllNERyy85uJ5lznzT2pLozb0hjmm+iq51xdz6CwDBT+PjB9EgTtd470yr+?= =?us-ascii?Q?o5ILnrSqdISHYmk3fw+3iaIJyzXA4fnmws0TRGCPvJaLGAP++X2qkfaPIiRy?= =?us-ascii?Q?UjvhjmMMTd0mNGQQ3h2gt1Mgb9jhPHxS5OfaX9YkFbpT6wvc+AiZ9Mx1uLm8?= =?us-ascii?Q?OHQ5DAKY6BUpLG+FrAtxRJEjP2zKN7sbbiGf41CSoECtsN4co6w+m/l6OsBk?= =?us-ascii?Q?769TtE+9ZAfwTzoR3b/yphIGaxJzaujhj0c6gumV5M127rhNKeQoTTwHA0hc?= =?us-ascii?Q?Kp2hKWVGx8XQJnJscKFlkJvuQFmXhG2+sgK560XTf1+VESw0/OSWDq3pkqZv?= =?us-ascii?Q?XHtlzXEvXGcv/bhjDKHxYW4E51i2XTwsXP66kyncuxHiBvqbIE8QG8032Vh7?= =?us-ascii?Q?H9+/42zzY2mxepmSK3gHnhnPWmecb8BExCQSnIMcxih+XmBRtGUbVR+A7o2D?= =?us-ascii?Q?28BwdtH12BX5vWfRC8oN2WdWv77gzy2JV3PuEWQ39HuXtLefFNDyHXvQ4HFc?= =?us-ascii?Q?l0QKPBfZhEk5C0WBtNENO8EbIFAdpwNBpINYyzIYnbuziczY56WLSPCvzIu5?= =?us-ascii?Q?8ySPiUI96hvl+qXYqL8ZcZk8jlmbxVQ60/9+FHCJ0a+ax5On5VyUrSsTexqo?= =?us-ascii?Q?Y4gP47Nk5BiF/D5IyAeJLf1kqglZO49yaSR4gZhpkDvdl3YJCnp6eqV22PA/?= =?us-ascii?Q?ghlg9Y4WS6Y=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM4PR10MB8218.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(376014)(366016)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?t7QRI+MczXPl5Yx2tKRlSQ8zw75NbwRf8ujvxeP2VmezAEFXs0Clh5K4HlLm?= =?us-ascii?Q?cojYexWbWv6iQpVxlZPm3fMhm2q38EDFFT+lLQuRU8tg0nzJjNNgsM7NkigP?= =?us-ascii?Q?djzL8G0+FlyB8n1W0TM8FoSC+zlhQGSBBKBnSkHBP1k3TiihyADejv1glCpq?= =?us-ascii?Q?xS0bJp4BxP8mXmGOAV/gOrfayNAE8iiPsY2PHH6nhBIZFWag16zPpAdfMEuG?= =?us-ascii?Q?kGkZLjPR+JRlsHfaUTYYr5jRoMh2OI8VaAoYoWpCtT+SaxG2So4D8c8lNE4q?= =?us-ascii?Q?fhiJAxnAVtx+7sUbyjn1ONP/7WHAXfKhTzTyhX5hBEeosRtvriUujFxHUjDE?= =?us-ascii?Q?JlEgJ7MNfnPlJe+qLWon2E3OnUay3C+a7xRIi2JjYoGIFhO7SLVFSUZxzMvW?= =?us-ascii?Q?JRyKJkTAIdSNBchUFU/w/p1jQMICnjvLZwayeKvZDRUVTXwndeB5aTKNe5Ku?= =?us-ascii?Q?ygVeexcKZKiq183uztON7vewAv5zqB/O7J/FRUIE/4b4zLPdrh+iWAvSVoHb?= =?us-ascii?Q?wgvpYaJmINUOhVy+zGNmqA25/JALhvxSGVp/QhZRexc0BUyruTwKsYH+5aDG?= =?us-ascii?Q?IIXh+B7UQPBlZeQRN+x6ZSJ9GjMeVdKneicJ2xHT2zt6MrD1r720/IqLQTDj?= =?us-ascii?Q?sqoQztfGoaT84mrunfqCXD934hfWJvi/A+dcId0ULg4C2qPKYB5veJERmqfE?= =?us-ascii?Q?FOSfUAyYhBCcuiZK6EIBon/409Nj72nKv9PVaP7lC6cMwxwV3d2oiEM9ys0Y?= =?us-ascii?Q?Xl9MGAn1qHlisMLhTpJ1S27ie4fY/k12ZKbg+bm8T8lOOKkTC5UIXewhRXjX?= =?us-ascii?Q?b64pfIVBzTQTGmtWcv7NDkm3L2PA9Sgyz2t+HvjtR/S8rEuTtqolYtgXX4M5?= =?us-ascii?Q?FONAIQ/xBSdJ3M6sgICoUGh8Zl+UV6WM/EnYMf1wXAHTN1xooCTaF50WLMwu?= =?us-ascii?Q?8zd9jfq8m1G2EqLKCTBlNA5qejw6GRqfCxyeMRtNTlp2dmPz30XrRxdJsjdL?= =?us-ascii?Q?F8AO+OVRgGgcNvpGo1lAiGSgP0lGnH3OTf5of6hDjZeLh+N8RNbmMELEp8t/?= =?us-ascii?Q?zbEAxXpy70sm+PTTOuTQDGTNH6/3Df5VZadCvlJE8hrh30u3rSREByMZgN2A?= =?us-ascii?Q?fp1Ji5EPsgqifIVW7lvt+GfmHa37ptg2jHvyMb6uH1gCswGp5xATaSfdET8j?= =?us-ascii?Q?Raiiv2MYUcyG7+9vUwDbjatEdbrK5aMKk5RvijwaM8BWdP6saN2OWxABr1ux?= =?us-ascii?Q?qgrXIiQ1n6dFas5owOZuhj4zgCAhQTorBxR7DXyMvfXWNhxW1D4LEvCbibF1?= =?us-ascii?Q?/5BcdJ7OwUa1Vc/4kRJijbByRD5TVoFkEaAS27DMLImv1a9WJe9SU7HrmIm+?= =?us-ascii?Q?KEjBxzeuCDHjtasuW526/w/z+qL60m8nMkLj9f/E6VETUj4D5vDavHu2hCWL?= =?us-ascii?Q?TvzFyeEkPlY8OLws7zJ/ne/FAMssdp+/m1/TIj+TzHotutRx07tBSYr/ZXp3?= =?us-ascii?Q?wTI4LagpAqQ1IrBHHDjvarEYB4MMs9PZDWV22nJODC38SjFk1ubSyFd65cZ3?= =?us-ascii?Q?kbBdrDuCd/qQJ7tBH5j6a0gd/sbtgvOl7sIGjyvE3pfBgRwrFUiKpWSSc/Cj?= =?us-ascii?Q?rw=3D=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9b300aa0-b387-4154-66f1-08dda831ee53 X-MS-Exchange-CrossTenant-AuthSource: DM4PR10MB8218.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Jun 2025 15:17:36.2739 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: VIHQqSurznSAT42qU4kEjWTCvDlhPhaM02AcyM/DbSq6lg27mUUlt4UvLpw8nGkDp54lG/Ta+ndnP8aYOANVCrh4t5sNAcNQtXiua3gcf1o= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL4PR10MB8231 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-06-10_07,2025-06-10_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 phishscore=0 malwarescore=0 suspectscore=0 spamscore=0 mlxscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2505160000 definitions=main-2506100122 X-Proofpoint-GUID: WWqXizaySfZG0u8yF7LlJAOpexlV-5av X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjEwMDEyMiBTYWx0ZWRfX/M7bsk4XJDi+ 8c4RnyYvhgix3SUjOV4wXXQFVajziNKDujsi9nfIV3lUb0a5lkvHbRNfkDx1IU10nsIIAaTvdyW Jg0hv2HeL2Xe/G3chLfEQ1C9HVNaeyxct+253J5cztYzozltIhO3tHt1WIoIfDod0xcbFqsaOhU 50gSTfR8RTMKu47dXjvlGgrLTKGOhbN9J1cKfW4oQp5n7An2zgohvQgQ4jEZUVpp3wR9Yb7a83H IyT0F5sEZwWTZnln0fjGzpjIw6x4OzltOPNzGiBshIrhcbsQGkddf8Mvk3rWHaYHqWQZcxWsi20 HmzEbRo7aJsFcpMauyxkhoAYnnV6VXFNKXPsdkCoEvFPc7an4XMdOv8xgyEIqH2Cnt51ZyK28QR R1OCpQf3cU3BuRCjyL548otWAHXsfXgwNmVN65/4MfqiSA0ZGb8jyFDiIxnYeN/U+DhF9Hbn X-Proofpoint-ORIG-GUID: WWqXizaySfZG0u8yF7LlJAOpexlV-5av X-Authority-Analysis: v=2.4 cv=d731yQjE c=1 sm=1 tr=0 ts=68484c93 cx=c_pps a=XiAAW1AwiKB2Y8Wsi+sD2Q==:117 a=XiAAW1AwiKB2Y8Wsi+sD2Q==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=6IFa9wvqVegA:10 a=GoEa3M9JfhUA:10 a=eKjrHVYcWXu7wmRAu4UA:9 a=CjuIK1q_8ugA:10 On Tue, Jun 10, 2025 at 04:03:07PM +0100, Usama Arif wrote: > > > On 30/05/2025 14:10, Lorenzo Stoakes wrote: > > On Thu, May 29, 2025 at 06:21:55PM +0100, Usama Arif wrote: > >> > >> > >> My knowledge is security is limited, so please bare with me, but I actually > >> didn't understand the security issue and the need for CAP_SYS_ADMIN for > >> doing VM_(NO)HUGEPAGE. > >> > >> A process can already madvise its own VMAs, and this is just doing that > >> for the entire process. And VM_INIT_DEF_MASK is already set to VM_NOHUGEPAGE > >> so it will be inherited by the parent. Just adding VM_HUGEPAGE shouldnt be > >> a issue? Inheriting MMF_VM_HUGEPAGE will mean that khugepaged would enter > >> for that process as well, which again doesnt seem like a security issue > >> to me. > > > > W.R.T. the current process, the Issue is one Jann raised, in relation to > > propagation of behaviour to privileged (e.g. setuid) processes. > > > > But what is the actual security issue of having hugepages (or not having them) when > the process is running with setuid? Speak to Jann about this. Security isn't my area. He gave feedback on this, which is why I raised it, if you search through previous threads you can find it. > > I know the cgroup proposal has been shot down, but lets imagine if this was a cgroup > setting, similar to the other memory controls we have, for e.g. memory.swap.{max,high,peak}. > > We can chown the cgroup so that the property is set by unprivileged process. > > Having the process swap with setuid when the unprivileged process has swap disabled > in the cgroup is not the right behaviour. What currently happens is that the process > after obtaining the higher privilege level doesn't swap as well. > > Similarly for hugepages, if it was a cgroup level setting, having the process give > hugepages always with setuid when the unprivileged user had it disabled it or vice versa > would not be the right behaviour. > > Another example is PR_SET_MEMORY_MERGE, setuid does not change how it works as far as > I can tell. > > So madlibs I dont see what the security issue is and why we would need to elevate privileges > to do this. > > > W.R.T. remote processes, obviously we want to make sure we are permitted to do > > so. > > > > I know that this needs to be future proof. But I don't actually know of a real world > usecase where we want to do any of these things for remote processes. > Whether its the existing per process changes like PR_SET_MEMORY_MERGE for KSM and > PR_SET_THP_DISABLE for THP or the newer proposals of PR_DEFAULT_MADV_(NO)HUGEPAGE > or Barrys proposal. > All of them are for the process itself (and its children by fork+exec) and not for > remote processes. As we try to make our changes usecase driven, I think we should > not add support for remote processes (which is another reason why I think this might > sit better in prctl). I'm extremely confused as to why you think this propoal is predicated upon remote process manipulation? It was simply suggested as a possibility for increased flexibility. We can just remove this parameter no? It is entirely orthogonal to the prctl() stuff. Overall at this point I share Matthew's point of view on this - we shouldn't be doing any of this upstream.