From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from DM5PR21CU001.outbound.protection.outlook.com (mail-centralusazon11011070.outbound.protection.outlook.com [52.101.62.70]) (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 C53983BED27 for ; Mon, 20 Jul 2026 07:28:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.62.70 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784532522; cv=fail; b=snEm3Ao7ZOd3UUehuwlCxtcDOo6Y79a6J8sHCq0pjT4qceNwwoC33LChOuICgh7rb3qiplfvmIAqQzzYKNjuhlbMKZJ5xyx6x5yMZ8acY7uEz8RaPxn5ZmQugfkN+4W7flFe+v0oyZPXV3GJARFGiD7zz/Q3/MsESD02+GC+Z4g= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784532522; c=relaxed/simple; bh=1yj0C6uiWZl2vhr7X917qy5nNlBinO40HO8ee36KdnE=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=iso/seBcaG9c5dcbveIw1lcaXnay+nrQL1cfGt9NZc2rRzzzqqIasaPgV4SwDLu+08m8d0g9+jcE2bXRRo9e8eifNA3fgnzyqlBn5wFhyVvMlC654K71loZDHPXnXGwb8mbgPeL9V6OPJcfH3KF9spjJZX8Jy/frIJB+tkuZKEA= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=KT7nhSvb; arc=fail smtp.client-ip=52.101.62.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="KT7nhSvb" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=j4AV5HZ84SePzbEkJ0uGX8NdKZpUNF7DvZ5nPh69HEQofMPyrzDimgOwxNzIEyea0HR0KmucUrCtX9QgOnsVU1E0FBUkz70Lcrfehsx+87zBdPNiEQNM+hCpibWW2FYfSklKUDy2lwuhPWIMaTid9F8BdYskbHJEsxPfRQsv9mMNtTim1pAG4Xhf5Wo0hW8MbnQOqNEMXnuom/v08XBgXa71V4RJZziepzYndHxP30hH+VUioXiiwgTXU/dhhhDSqIn4CGzQDVAOVuw2A+aAjAEh88yZsAw39GyLd3ZHHIi91c8+siITWu0D9EdCWEMOB46NQivaseL4a70jhIax1g== 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=tLk2RJptM/6d2VVBlVWd80Hp2X/TjDlwN3l1Qtph/rQ=; b=A9tpgxK0acS+HH/W7xdVSq2bWZ9hpFm0pPz0Hjw4/1YmHoeD6Yw0oHlTzL7ylwYGQbPmEMyGNbp+/jh0vM1sZmYQSdTg0uVVSwkkLmDBATVAS3wT/I8qJYTn+G+CSFK12QULI/ObvLrQj5oxKHcstyV2srwSecUtUaYpCVLcPPqunN0t2ky/CjW02p5Y+Lj7kfAZcwR/NlnoSdy1q0XuJ2AvIt0IYphs7kgXKSNfeW7P1E/bR6q6eyORaGTKCAU8GU4Y+CoocnkooF61gfcgG+3MAnVjSt30qQFCgMwD9j0U7zSZ8uDYKweMB8UpFrLQEjg0MrL2YEYGnUm/gVNd9A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tLk2RJptM/6d2VVBlVWd80Hp2X/TjDlwN3l1Qtph/rQ=; b=KT7nhSvbVQXHqUJaDWMxGuE/uzF/7+pWg7EZXTWSSrlf7W1lYkhyrW5SD4B3LQT+9wwVT6PMYgAzM+xk+C8r07XTkrLbINFW2Me/qB9sZpDAUVr4rmMPUVTZMacI2adta9peQJoVrkFnZ1McIlCRwjzObYoUo79KVX49hhKQnpgTLGydmnoFF8mKopxOh+kP+/E/5lSOkJ57wxC8uDwt6Q1Swu0qYvtC9OETjK5MpOZi0gJNO4Rp1+8ehyDk45FJwIdH6ZhLdzBBg64vvomckzr/auBwwqWQk7fpBais+3b9V10UNQ0Z+yvYApR0Z82pSNHcA/Yw7KchtXQ4eaH0HA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from MW4PR12MB6802.namprd12.prod.outlook.com (2603:10b6:303:20f::19) by IA1PR12MB6259.namprd12.prod.outlook.com (2603:10b6:208:3e5::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.223.16; Mon, 20 Jul 2026 07:28:29 +0000 Received: from MW4PR12MB6802.namprd12.prod.outlook.com ([fe80::51f4:a3d9:b44e:9587]) by MW4PR12MB6802.namprd12.prod.outlook.com ([fe80::51f4:a3d9:b44e:9587%5]) with mapi id 15.21.0223.017; Mon, 20 Jul 2026 07:28:29 +0000 Message-ID: Date: Mon, 20 Jul 2026 10:28:21 +0300 User-Agent: Mozilla Thunderbird Beta Subject: Re: [RFC PATCH] mm/khugepaged: cap pageblock contribution to min_free_kbytes To: Zi Yan , "Lorenzo Stoakes (ARM)" Cc: Andrew Morton , David Hildenbrand , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Liu Song , Hao Peng , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260716173504.760369-1-noren@nvidia.com> <8E9B69B5-0FBA-4CE5-B737-B83AD1FE52C3@nvidia.com> Content-Language: en-US From: Nimrod Oren In-Reply-To: <8E9B69B5-0FBA-4CE5-B737-B83AD1FE52C3@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR0P281CA0175.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:b4::9) To MW4PR12MB6802.namprd12.prod.outlook.com (2603:10b6:303:20f::19) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MW4PR12MB6802:EE_|IA1PR12MB6259:EE_ X-MS-Office365-Filtering-Correlation-Id: fb1b3888-63ef-46fa-b4fa-08dee6307e96 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|23010399003|7416014|376014|1800799024|18002099003|22082099003|11063799006|10067099003|56012099006|4143699003; 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:MW4PR12MB6802.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(23010399003)(7416014)(376014)(1800799024)(18002099003)(22082099003)(11063799006)(10067099003)(56012099006)(4143699003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Y0g3YVd6bDJiVWVTSFp5LzFodi8rNkpEb1dlYW1lVjRCekhwdndkUlFmRW9r?= =?utf-8?B?YTB2WDlUVjlyU3Yvam1FV0JEajU5bXJ3aE1CcjJqT3B1endkZWNuZWUzVG5P?= =?utf-8?B?QUNyeE55OVFHdmF2MWNOZnhFNWlWTzNDa0QxeENvaG9YSHVJVjNKUWlhb2ZR?= =?utf-8?B?UzV0RzR6TlUzVkpOOHFRb044RHJZaGF2WDVzZDhhalpRbjJqU3pSQlUrendw?= =?utf-8?B?d21mYWd3elJpV01GNHNMVitlZjJxd0hOMTltVWZ3cXRyREdVKzYxMW9uVmV5?= =?utf-8?B?RWVFbFk2TUI4RCtSdUZSRmdCZ2FCd1U0aXV1QUxXdW1NUStkeHc0Q2hDMTBM?= =?utf-8?B?S0M1Vkl6U280Y0E1ZE5NTm8rQVNRVWl4QXpWODlFT01GemtqSlc5cC92M1dI?= =?utf-8?B?cDZLWTF6Wi9RKytVNHE0ZkRxR05la2VmUG9zdHU5Nks0M1A5ZzQvZThGY1Vv?= =?utf-8?B?YXFiUmtrUm01b2lQZE9Lc0hBNzlUQThDMFdPcjUwZlZnN2gxWjdMTUg3Vm9s?= =?utf-8?B?RWYvSThSV0drOG9BNU5UYlNnc1Y2LzNsN01IbHYxb0gxNC8xem9GNWdKcU81?= =?utf-8?B?alRZS1BxaGNoOUMySkd2ek5aN1JPY1dxOW5zdVZlYWdYbEt6WHlJRFRMMXFF?= =?utf-8?B?NFVhK3ptZU5MSmpZYVBERngwYk1LcEFZYjlkVlZlTXVVdkgrbzNCNHdIK1Rn?= =?utf-8?B?T0FvQm1ldGdaS1hqcHdkRk9KbzNoK1NRT1A4SHd1LzFFMXl4NTNRT25hVERW?= =?utf-8?B?R0k3a0Fwc0N4U1MyWVBueFlTSW1WbEUvVnJ0MWxRdlM1TUdjSUV2SWM3cWhI?= =?utf-8?B?UXdYVXZhMWpMek8yemZIdDh3amJrbnFlTUNFbXdSL0FqbllhMFBOQ0Q2dHlR?= =?utf-8?B?QXFCOVRBQUxtMlBuWGNGTThjayt5dGpuVmQyaTZxMkkzMGlZck1McUVsVkxZ?= =?utf-8?B?WjEyNVpSTUMzNU9xN0dJcGlVYzZ2eFltandpYTFEQ3VUYWg0VDVQUXNMN0Fs?= =?utf-8?B?Wk9BUGRPazRtTmVyR2FIc3ZTS2xWVGpDOURUalhkeVdreVp3ZnVOV3hlamk3?= =?utf-8?B?MnR5aXM4QVNxbVJ6YjlCZERwc1lhTGVvcklrcTJPbk1NREZTZGVoS3R1V3VM?= =?utf-8?B?NEx0TGVkRzFGV2ZUSTFqSHMxWkNKdVByaWh4dWt5NzVTSjZWZkxUTUR4WFpq?= =?utf-8?B?MmorWElnSDJCc2dEWjUvZ2Zhd2ttRTczcTl6K0pLZ2c3bnlvSW1OdFVvb2dp?= =?utf-8?B?eUxWcVVIcTJRSFFLNUZ2Sjljbnhyb0NFcmxFQzdaZG83cEZiV2N6ditBVXFv?= =?utf-8?B?QXE2STVvcUZ3YmJkWlVvOUtmRkZFZGdvdEg3aW9UTVJCKzA3NWc3OW9oeG0v?= =?utf-8?B?ZHh4MDMwZUdWTU9oYUJKVEYvcTR4YjBjd0xwNFZqcW5lTGJRNms5Zyttc3FF?= =?utf-8?B?NzQzdlQzbDRpZGR6eldFRUFyaXNyS2NlQ2pHK0F4L0tCb1NHdG4wcGZOM1ZU?= =?utf-8?B?M1V6NThtdHhqK1lrRFpoNHkvdW1HaDM0STRtd0tGK2RRbEZSVUJvckVCTmlw?= =?utf-8?B?VmhVTFQrODlNMHduaEZ5c1B6Ykw3c2k2K09mR3hVUzdqWW8vVVVsOFBxRlZw?= =?utf-8?B?dm5mYXVlM2JQMlQxVlQ4b2x5RTdkUGJhVEh5UjQrcjRVMzlEMFJsMmFpNW85?= =?utf-8?B?elFmV1B3dGFLUWFOd2YxVTZGdHhUK2N1ZzJrSW5FNC81djhMcXJhcS9yY0Rh?= =?utf-8?B?MlAvR2J2cnlnMWZ4UHl5djQrc3VnK3J2V3plTGZXRi8yMWx3dDRwQlpPbVNs?= =?utf-8?B?YTljbkJoRjRIb05IMHZhcDh4SVQ2M2FQOENHV1ROTHgvRHV4TDB3QVErZGd0?= =?utf-8?B?RG5HTlpJd2ZSQktjSk1scjl4ektZZzhkMVBUSDZHSnBodnRXZS9pVTlnZkdp?= =?utf-8?B?UTNORXo1VmsvaW01V1FzeWZIK0JYNUM0aS8zNWpuRVNMVi9oTGdSR0dTaEh1?= =?utf-8?B?aDhUdUN3V1laNEhVRGgwS1F1OUFwWS9xcm4zUUtIRFA3aUY5TXNISVBQRlkr?= =?utf-8?B?NXFhbFg4R0ZJOURiVjFHSXhuOFpBNW5QRjV6M1lmTEdacTZEMzA2bE96TDVQ?= =?utf-8?B?VGRZamdFbkgxVWxLZm10ZUtNRjk3bU1IS1NWSS8vVnlOdzRIYmo3T0ZQME1S?= =?utf-8?B?ZTJjLzFBZ1BzY243bXcvT0RmTjlrVmJycitTMFVHU2I2eStNRk94emZFTlVp?= =?utf-8?B?dGhNdWhMNFlCVktsYzFYbE9WNDJncDdUTkRGenBQYUZzMGxETHZwOC9jYmpl?= =?utf-8?Q?HAqlvRAzRrQAmiFofD?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: fb1b3888-63ef-46fa-b4fa-08dee6307e96 X-MS-Exchange-CrossTenant-AuthSource: MW4PR12MB6802.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jul 2026 07:28:29.1776 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: C4zmOWQUp910Rk2EF6gGI8Eh84SK513xYxIu2ndIwIyv3kf6m0ja5iJ4mokaXKLY1eXMkXFG5hskRYkrCHCW1A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6259 On 17/07/2026 17:58, Zi Yan wrote: > On 17 Jul 2026, at 9:36, Lorenzo Stoakes (ARM) wrote: >> Maybe a simpler version would be to just attack the issue we actually have >> with it - it uses too much damn memory :) >> >> So maybe something like the attached? (you'd probably want to make this a >> sysctl or at least a defined value of course) > > The approach below makes sense to me. In terms of the actual cap size, > I asked Codex to check what possible pageblock_size and their reserved > sizes: > > 1. 1MB pageblock size (s390) and 11MB per zone, > 2. 2MB pageblock size and 22MB per zone, > 3. 8MB pageblock size and 88MB per zone, > 4. 16MB pageblock size and 176MB per zone, > 5. 32MB pageblock size and 352MB per zone, > 6. 128MB pageblock size and 1.375GB per zone, > 7. 512MB pageblock size and 5.5GB per zone. > > 1GB makes sense to me. 512MB might also work. > Assuming three eligible zones, my original proposal would have been equivalent to a much lower cap of 66MB: 2MB * 11 pageblocks per zone * 3 zones = 66MB Using a more conservative value also sounds reasonable to me. >> General idea is - if we're going to cap, let's just cap instead of >> pretending that page blocks are of a different size. >> > > Sounds good to me. Thank you for the suggestion. > Thanks Lorenzo and Zi for the review. Capping the final recommendation directly sounds good to me.