From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=memverge.com header.i=@memverge.com header.b="BBykjkBh" Received: from NAM11-DM6-obe.outbound.protection.outlook.com (mail-dm6nam11on2065.outbound.protection.outlook.com [40.107.223.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 438211B4; Mon, 27 Nov 2023 08:15:04 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=R7quJ0/JhwPoe+pjjBa+dIpSHhAZfAqMR40VItdl9NPp4i/GdC4a4fG/r6qeWApLWnbnfOmHKtW63CZJvLkrfeQjdbm9AYiWNqndySDjXMZBb9cLzBc4Fe6YGsuRNNi5BgYhsf36GaqPYKs68+2sVJwxQFLNk7Evbw5MmrQPW1aYOG9uLa7ZlcIAfhGGE+Un2StoA1mNPSCGTMrDoi4/ZBaPJW1o6O9e7+Q5WXaJur4EgsY+jzDy+r72hbjgG7wGDGPpkqlfPkLtYR2QpdSvLU7uQA2W0RL3NIq7I3AutshSZeYU0R/tBwlbBlA6Xr3GDzpu1pume3mNI74TGsZjqQ== 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=D1Aw9pyMUxxgXTGggCIAPDiOg8gt/pGqW9ZRsYPBCHs=; b=kcmm0DCs4Zex+vMBVnh9RM5nRRmao4GICkhzVtYwCCYuCdsZ9u8e2l8S6mkFpCbaQN9zpQLceZDGCcZwen9KmqkM/JUfKZIHDxFKKRDQoKz5jEyWXvI/qSp7uUTsnfv7DQVDbodrf5BGou7kWbUzvH7ZsCrz2FnLJpJ6/j1rAuZHbDk0jXpDnM5uOkW9ntj0sRt0hanPueuvmrDZMfuQqZImj638qlzASUQ7M+KCGfihtJqZmpYjC3XwzcDRjc2z2b/xA7L/RkimtvUPRSs2NHmwD8CvWgrkB0vhEPX6XgTOpaQcxHzD48+lqgqE34QgtcCLyXjwupgIfjrtQjlBmw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=memverge.com; dmarc=pass action=none header.from=memverge.com; dkim=pass header.d=memverge.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=memverge.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=D1Aw9pyMUxxgXTGggCIAPDiOg8gt/pGqW9ZRsYPBCHs=; b=BBykjkBhmXAEcUZsNoYM+diuwyg0QPKWathNjmg1p8vsYOKpJPVfYpS3sZvu+Xed2eWpbR/W/YFuMh7r7mOsUWb2rp8l9HppRurUFjdimya5LPswf2FeKtnPtj+zLdmNmmiXL/hZBc8mn/ipnNP47frLqZNQ7KR5zhRradSJ6dw= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=memverge.com; Received: from SJ0PR17MB5512.namprd17.prod.outlook.com (2603:10b6:a03:394::19) by SJ0PR17MB4837.namprd17.prod.outlook.com (2603:10b6:a03:37a::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7046.19; Mon, 27 Nov 2023 16:15:00 +0000 Received: from SJ0PR17MB5512.namprd17.prod.outlook.com ([fe80::381c:7f11:1028:15f4]) by SJ0PR17MB5512.namprd17.prod.outlook.com ([fe80::381c:7f11:1028:15f4%5]) with mapi id 15.20.7046.015; Mon, 27 Nov 2023 16:15:00 +0000 Date: Mon, 27 Nov 2023 11:14:44 -0500 From: Gregory Price To: Michal Hocko Cc: Andrew Morton , Gregory Price , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, arnd@arndb.de, tglx@linutronix.de, luto@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, tj@kernel.org, ying.huang@intel.com Subject: Re: [RFC PATCH 00/11] mm/mempolicy: Make task->mempolicy externally modifiable via syscall and procfs Message-ID: References: <20231122211200.31620-1-gregory.price@memverge.com> <20231122133348.d27c09a90bce755dc1c0f251@linux-foundation.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SJ0PR05CA0085.namprd05.prod.outlook.com (2603:10b6:a03:332::30) To SJ0PR17MB5512.namprd17.prod.outlook.com (2603:10b6:a03:394::19) 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: SJ0PR17MB5512:EE_|SJ0PR17MB4837:EE_ X-MS-Office365-Filtering-Correlation-Id: 0f5061f7-f429-4a1f-5661-08dbef640102 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:SJ0PR17MB5512.namprd17.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(376002)(136003)(366004)(346002)(39840400004)(396003)(230922051799003)(186009)(451199024)(64100799003)(1800799012)(26005)(6486002)(2616005)(6506007)(6666004)(478600001)(6512007)(38100700002)(36756003)(86362001)(5660300002)(44832011)(2906002)(7416002)(66946007)(83380400001)(41300700001)(66476007)(54906003)(66556008)(4326008)(8936002)(316002)(6916009)(8676002)(67856001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?9gI5u5UaE+LGl1pKWYmuVOx0Ppzy9Kf0xMqJk/wODCjJ25bngK7y4aEx5uWT?= =?us-ascii?Q?bsQshGTLqnNVg2UX9Zq95qHvP5aV2aK2YaYsEiRG+5tlEKmeACkf/38wvUt3?= =?us-ascii?Q?lTOUl9j1X/TzgO+Rh1s5/NrXyaeLDL+z3JZJiuVl8rpVKaBUl+4vWX03b2Zb?= =?us-ascii?Q?btiJDb3V5zWPMsZkjDii7OOSQoSUUMSseaWj4YUuaGTOQer3REQvUrZ+Syaq?= =?us-ascii?Q?gQ+36nCKaWLHnnf+WaQvKqswyxxzJUr3w8jmHD5GnULVYGn49NHttYyYxCcD?= =?us-ascii?Q?+COLAaV5OaNh14coREDz1MQrhdHcpkw1+FKGM69I7HAy6C29ZnlStO0FvwV5?= =?us-ascii?Q?AaH/1azxyEmsvqWnH34h7hhg7THGRVpFcIjq2s2rytLZvsM3Ni34JQO492T2?= =?us-ascii?Q?MupfxMTW0ACLZRsB47YMWD+sQkFjlCdE/rac6N4K5TFN6dsp8bdjM6mS/bKW?= =?us-ascii?Q?9QBhgnbX+YRyKdurgHipQ3+8LFYwu5WcBLeRvPJfHfiYP6gBrhxJfv2htmEX?= =?us-ascii?Q?nz2Ltq+NNHf/8cCYoJPvqkESSZpRk+ZBhIUs1gaHEzQ45NIipbpYcHUPzsG0?= =?us-ascii?Q?nTS4z1sy0ZG+adGrdigl3ErbJbV9lfkC8tZI0u7V2FEQLZmM8mz3g+ai5DQO?= =?us-ascii?Q?Mai2DlQXO0MW8cT1wx4EiSC42/XH/FE5Hfua7l+X1is/L4GAGbHRh1sXiZhH?= =?us-ascii?Q?9nnvdTUkt7sGKPmgi9ma193hZnV2aD+rUhU8idLLpFMn81hvBYpQZXabc3V4?= =?us-ascii?Q?P9l2nEr4IMJKb7M6vPAOtcVADNlUFWpeETo/laWtyzoRcUuFSP7Eck4JkTNr?= =?us-ascii?Q?zXTBzZeohNW8tGR/kZMcwjk5vdGhsOLhQS2JGOez+41cDNaoKPabnxUhC6uL?= =?us-ascii?Q?f9+yuGEmeLEUvcsu2zIIDBkjnLGWRo/t4dLSTyzaFYScOwm3QJiNHAZDD6Fm?= =?us-ascii?Q?rG4Uj5QvIuhysekBrUTTh8L9kxxO+0praaj97j1yBKMC/UkjikujTDl1L99R?= =?us-ascii?Q?yfG24+O6nMHo9fxnA5ZrprI7CrfA4UbM+/NUPU6pOM4p80dnwtToH1JyJvnZ?= =?us-ascii?Q?gs/1uOIWRW74dYX+lQszGG/DHKT64eFjSj7xP6E9eZPLwsUj6FlkjZd2vrTP?= =?us-ascii?Q?gnUpZse8uHSonlzmfIYp/IM1TR3M6keTw1joVGjW6WJiDVBDemUkI7luHRmx?= =?us-ascii?Q?GlYlR2dgOEKURiKjXKzTrX7IHpzKvsmVe6DOj7mL12t0+S/yflNw2wbe4ayR?= =?us-ascii?Q?LxGfq2LJF1KjDhM0hgKhEdOI3BaIA7RamK88qlzdTw70dCOAHd80h+aIB1wQ?= =?us-ascii?Q?qfSqvCG+YzgU7r2rZCnlpTV3Qtd/VIkQxnSKg8yzw5TUdmSeZVA4t7bjm0Qw?= =?us-ascii?Q?nFUzQtcGNR3lut7WDrS2IRp+5LUWxYcrvX2aUavoj4+PO/Z9bLOqBL4VmOAh?= =?us-ascii?Q?4PRGRk/GspeGwvURAPiYrcrW3otGRso7u/5di3ukpM1LPI8+a1oF3/FjabfX?= =?us-ascii?Q?BHHYdcE8VE0sVXTHu37OkKao4Wi8zF7h4pGNKi4KPD9bIP70jlvZHpNfGz/a?= =?us-ascii?Q?mhjcZAEDG7pUQ4yRk9pCFB3Yx3UyQ4S3oA2MINGPz0vmkT6raTwpxjpbgKO5?= =?us-ascii?Q?3A=3D=3D?= X-OriginatorOrg: memverge.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0f5061f7-f429-4a1f-5661-08dbef640102 X-MS-Exchange-CrossTenant-AuthSource: SJ0PR17MB5512.namprd17.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Nov 2023 16:15:00.2107 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 5c90cb59-37e7-4c81-9c07-00473d5fb682 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ChMJJSg0PJsS3DAKA22nMf8nmlg7MiEnWkm4s5pZ7tDEN4wE9yLeB3LUT4u+p9jdv1jtDa3ISpxHUZae18WKSK3By/xgIdtYeIClLTGaaYI= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR17MB4837 On Mon, Nov 27, 2023 at 04:29:56PM +0100, Michal Hocko wrote: > Sorry, didn't have much time to do a proper review. Couple of points > here at least. > > > > > So... yeah... the is one area I think the community very much needs to > > comment: set/get_mempolicy2, many new mempolicy syscalls, procfs? All > > of the above? > > I think we should actively avoid using proc interface. The most > reasonable way would be to add get_mempolicy2 interface that would allow > extensions and then create a pidfd counterpart to allow acting on a > remote task. The latter would require some changes to make mempolicy > code less current oriented. Sounds good, I'll pull my get/set_mempolicy2 RFC on top of this. Just context: patches 1-6 refactor mempolicy to allow remote task twiddling (fixing the current-oriented issues), and patch 7 adds the pidfd interfaces you describe above. Couple Questions 1) Should we consider simply adding a pidfd arg to set/get_mempolicy2, where if (pidfd == 0), then it operates on current, otherwise it operates on the target task? That would mitigate the need for what amounts to the exact same interface. 2) Should we combine all the existing operations into set_mempolicy2 and add an operation arg. set_mempolicy2(pidfd, arg_struct, len) struct { int pidfd; /* optional */ int operation; /* describe which op_args to use */ union { struct { } set_mempolicy; struct { } set_vma_home_node; struct { } mbind; ... } op_args; } args; capturing: sys_set_mempolicy sys_set_mempolicy_home_node sys_mbind or should we just make a separate interface for mbind/home_node to limit complexity of the single syscall? Personally I like the dispatch for the extensibility nature of the arg struct, but I can understand wanting to limit complexity of a syscall interface for a variety of reasons. ~Gregory