From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CY7PR03CU001.outbound.protection.outlook.com (mail-westcentralusazon11010006.outbound.protection.outlook.com [40.93.198.6]) (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 C030017B425 for ; Sun, 9 Aug 2026 02:46:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.198.6 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786243588; cv=fail; b=XNEuB8LrxYC/sn+29s8vxAbpTb9LrbqjmDWryDgWg8YcsWwgwnBJgSPGsV8GPfpRuT7QuGG23xam4RYgM3lj1opDO8iKB8mE1mKyGDm2Cf2R9YKsCT+8mUOeU8pDVQy/6UmKLpEUOaZfjaWqZWQyvVRzPtc8per/2HZocH/JbR4= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786243588; c=relaxed/simple; bh=tZviD0SCQx5JXjuN3AV4vuNCWxHplBAmUkpVmNCFwgE=; h=Content-Type:Date:Message-Id:Cc:To:From:Subject:References: In-Reply-To:MIME-Version; b=b+RBsCOhJDWv6r/i04M3TT8jiRFZ8jfVxhQaLCgWhScKEUAAvg1h33w6rFMII+sEhMbGchzazOw1D05eSCNlEsRfmPFr+so5AwBJF/3UNgxx9DYr8MsfhQ2KY/1UfPN6ehfiVGfpqvs16AS0HnxLJ7tUo4xip3nflI4WW5Zd+J4= 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=oA3+/uFd; arc=fail smtp.client-ip=40.93.198.6 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="oA3+/uFd" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Uyg+Th1o+B/00u7oZ+5rUE4jzhf+9SHAX9lOEnpeCOh/fBhz1N+5+nQ9aBTY9X/k4qedKFGfvVJV3jwgJc3qE+Dw6DmW8+QufPE5ZK//K/FhfnFoGOU0hpkEW5g8Eeq9IBHsTNBXaf8EIEWyuaut8Obv8pl/NuhLsHvzUi7hl44z0TP3hyTcSrjYGRjUke/EPJ14op+Rv/w/6FsXy0y41pgxf5YNRAbnor9cM83W7+gnOFj3qZ1Zl4IDfm2Ta0sq90Nblxhc5iTZbgHShCsz7gV172g8oWuKquCeJraduk44lhPkK3dxUMIAAJec2wKHaras9IN1m5KByr3cWs0srQ== 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=X/tMtaUP0qDQqX75sSzSv9OYCsZRvD5YbQxLwFKgY/Q=; b=usC22nEu/vtjnbj8gnkBNLb0RjBAcpOHqCzX2bNtT670OJPRHmxOPoIzIY12Kw9e5uS1iUT8kvI3MRHFG6Fkz+y8dNymOQd/6GqF3PD3/XMnpYMDgFLbe640LdmayWGKvMTIwO+uP2J/GkM2fTxXi6Bhn/kWUw2pw9/VPFXtO7fNd+2GQAktTKV4IXTXvMraOWclpKa2cTUfnO8/qwSW6BbkqHVaghZK0BPyQDt0GLS20PImuwbqZE89KB2iYLn6xKnGl+vH9T9PlmJDlbBAE4h4/4gZxii9XAFw3VyNZFf0sZviBqJwNJEN1SZG1G+vDAReE4HyG2iM+JspDcZtUw== 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=X/tMtaUP0qDQqX75sSzSv9OYCsZRvD5YbQxLwFKgY/Q=; b=oA3+/uFdw4mrMJG9b4yF7YMdD+00fp5pDC/VryvxbP1VaNYX600YpC0PcfMSrX9OzrfCaFz+xBqyZE8wS5Vw6Ba/LKRLDZLXkoGa7v+cwQ2x3B8sqrZX7OQkLPy/mGHfNeHrIXdnEMwJgUziQEaR+aES7osciUnLv6r4KDy7GZ4gqdZMbDCRwtfsM9wIoYEXPJBtvfLxzvJrTW/CRXqlXUUMMaZ2lZ+/EZLg7n7sm4G6PnsqjdI1rWQhkgXLV2jq39OW+2wppS2S/huOo02vcZb6X32+f8q7ibQE2U9VCkJiThO0P1+QJJ4js8QxTpTdCEueJ5Omwt9oVAb1ItiqtA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) by CY5PR12MB6648.namprd12.prod.outlook.com (2603:10b6:930:3e::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.292.19; Sun, 9 Aug 2026 02:46:23 +0000 Received: from IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16]) by IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16%5]) with mapi id 15.21.0292.024; Sun, 9 Aug 2026 02:46:23 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 08 Aug 2026 22:46:22 -0400 Message-Id: Cc: , "Andrew Morton" , "David Hildenbrand" , "Lorenzo Stoakes" , "Baolin Wang" , "Liam R. Howlett" , "Nico Pache" , "Ryan Roberts" , "Dev Jain" , "Lance Yang" , "Usama Arif" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , "Chris Li" , "Kemeng Shi" , "Nhat Pham" , "Baoquan He" , "Barry Song" , "Youngjun Park" To: , From: "Zi Yan" Subject: Re: [PATCH RFC 12/13] mm/huge_memory: lift order-0 restriction for swapcache split X-Mailer: aerc 0.21.0 References: <20260808-swap-thp-cleanup-v1-0-689939a7ccc3@tencent.com> <20260808-swap-thp-cleanup-v1-12-689939a7ccc3@tencent.com> In-Reply-To: <20260808-swap-thp-cleanup-v1-12-689939a7ccc3@tencent.com> X-ClientProxiedBy: BLAPR03CA0049.namprd03.prod.outlook.com (2603:10b6:208:32d::24) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) 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: IA0PR12MB8374:EE_|CY5PR12MB6648:EE_ X-MS-Office365-Filtering-Correlation-Id: c72523bb-d762-4606-9492-08def5c06658 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|23010399003|22082099003|18002099003|4143699003|11063799006|56012099006|6133799003|10067099003; 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:IA0PR12MB8374.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(376014)(7416014)(1800799024)(23010399003)(22082099003)(18002099003)(4143699003)(11063799006)(56012099006)(6133799003)(10067099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Z2o3Tmo0RVRGS3Q0b1JQUmVISk4xYTFPdU5Ga1V5aGlIdmkzb04xQXo2Nkw1?= =?utf-8?B?bUVoNy9XMGRpaVRHM2dYY01IMzQ1ZVpwRVFyczhKd09XT0dTNStESVo5Y0hp?= =?utf-8?B?bHNUbzVOUEYzUmE5S3lvZ2dkL1owUU9yVzFaMjg1aExFVWRKNGRUcUpLZ0kv?= =?utf-8?B?NFYrRTF3b3BvWVg3SEJia3BydUdvZU5PMTlFTGs3bVZTSGUramxMem41NURD?= =?utf-8?B?SzRJdm9UT3ZvOHRZR29lVVZhc0lyMHU1TVhrRDZzUVg0S1hxa0NEZ2dXWkZr?= =?utf-8?B?NlY0REtCVHhobXNvQmRXR3R6ZWExN2gxK29aSmRnSUJpZ1o1OUtaVW9hQkE3?= =?utf-8?B?YlpwTGlObnljSTMxV0FoSXJ2cko0UUpXTm9EZDVaSUFWSzdGRmF3UjdYQnZx?= =?utf-8?B?MDRtUzlpeUFweWxHaWgvU3VZTzgycXpacDcrRWVhRTV3Y0hDUVhObDdNc3pN?= =?utf-8?B?enlTVU54aWZvSVlUQ2NlUmpndFNiUkZEOFVUeEVMSGJPOU5IcGZpckJQMnk0?= =?utf-8?B?NGRPOVRkNGVQUHNmMkIxU25YNlY2SGE5eDBTVmIyM1RjV3A4QkJoWmx4by8z?= =?utf-8?B?RXBta1Znb05TSWFodnlyVHVQc2s0bmFVQVhlcmpVRHhGRE01cGZDUWRLamxX?= =?utf-8?B?OEVUL1h3VHREU29QZ0JIa1gvclA1WVl1WFpOM2Z4Slc5YlpibHZ2NWhSZUxK?= =?utf-8?B?QnZwNlFwUkdGOUtZMHc4eEpwclhSd05qQitkb3pPUHRvWFl0YVAvbGVnQ0k2?= =?utf-8?B?WHdVbGxydUxnTDdVMEhWcHdjQ3gxRStDc3lFdzNxOWxtWlRxZDlndEgvQW9P?= =?utf-8?B?YTZBVjFjRFdNRjRpYmVUeExYeTBacmtWT1libW1EbWRlUVBQV09EK3RrMGNW?= =?utf-8?B?VFlmMU1rVCt1NmI2WXNiN3k5d09vY2s4cjNxZC9ULzJ6MjA4cFNRZjBlcCtu?= =?utf-8?B?RVBZaERaNHlHWEQ2YnY3YTI5WEs2QUV1RU8wWC9STG5DVU9rNUVVRmdZZkRl?= =?utf-8?B?dXEwTXFzTmJHOUFWV2svTTlXUTJOK01TNi94eS9EcVZoYVlXeDV6dmxuZHI5?= =?utf-8?B?d0llMkN4QytlS0RQV29BV2phb3BFaVBMN0U5VHlkbk9obkVDK24rd3M0c0lU?= =?utf-8?B?TXVBRHlqRkk1T2gzTmxMZ0lDMDBIZVB1Zlk2TnVnYTBCQ3VZdm9kZ3pMZmp4?= =?utf-8?B?TERjbU9qS3czZmVDdXNmdVhDekM5UGlTSzZjdlhGYlJ2d3ZJYytGVmYzUjdi?= =?utf-8?B?TzBjZThDYlZVbzh3UDVPNDhyUEtYOVlaMnVjOTFFb25nQVg0NXArVzZPOTdV?= =?utf-8?B?TW1YUk9EYzRBZzB6aGhnMGNmZzVnMzZ2dVVPd1lRNUllUGhFalVIclhKV20x?= =?utf-8?B?MXN4TFNFYjd6MldWZVExdnY4Q1lmQTR0ZWpOdmwyUys0YmwyaGhnTXd3Nmhj?= =?utf-8?B?c1c1d3hTQTg1ZGUwdlJhck1tdDhUQnpRWHluSHlLdmZ4TVIvdTZmeG1OKzln?= =?utf-8?B?WHlwdnVuU3hKaXFVNDVaeGhxSzVHRWhtbm9raG5xaWtZN1hiV1pCVnJMSHdO?= =?utf-8?B?ODBoYUE5eDBnT2pCL29UdFg5SGEzRnlkSmRwTlNQTm9PZkpub0pidnF2T1ov?= =?utf-8?B?REZacGxvMjR1eGlLTHg5TGQ3NWYvWi96SnM2RkFUakdCZDEwMEc5ZjZYL0FZ?= =?utf-8?B?NVFuOWVyNnBHY3JnT0Jya0xEQmJPSTVOaEVjNlpJSzFENW0yYUJRWnVLT3Ix?= =?utf-8?B?TndKZ1FIZUdXdzl6SzlEQjRkZk5FeVppMHJlNm5pUTdRV3ZnZXgzejFIQm1i?= =?utf-8?B?MStOMStrN2J0eXBaMmZRS2JaT0xGbWVpQWVEV3RaY0NMSm1RQ1lSdjZpdktO?= =?utf-8?B?MUEzMHZMZHFFRjJVSTBvNUJXdHk1UE5iV2Zac21mMERMRXhqcWFxOHNJNjJD?= =?utf-8?B?T2gybEtiaXEvcE9ZVER0VGJoN2EwR1RKYUNuUkF6c0I0Tk84R1Vsd1o3cjZO?= =?utf-8?B?WEtzeEZhSGVad3RDMmV1UlVqdTFyaDhzOWJrVE9TUVJrNHdndUJUcWxCSWZF?= =?utf-8?B?cU9peGxDVytHbFkvUzg2VEcrQlFKeUtLa3lJNTAwQUN4UVhQd2V1a3ZBT0tW?= =?utf-8?B?cUlKb3kwQUJuWm1MQTVHQThON01rVkRSZXpXTzdsZGJzSzN0c3JYZldvMVlU?= =?utf-8?B?SjVzdjRZQzEzOWE1eExPSURTMHdHRXZCbjF5VDY5byt4YUw1Zy9NTi9zQWc4?= =?utf-8?B?eWpnR3lnMmYzZS9zbTdOVEdRZ0xRbk05V2UxazdsOUNuRU1tbDJGZkczd1ZT?= =?utf-8?Q?h804+cxCGiwuR96nMk?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: c72523bb-d762-4606-9492-08def5c06658 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Aug 2026 02:46:23.3615 (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: r/CdRWkEavd6tz+2IIiva9CZRp4IYTOu/VI90qEfECF0VMetxbyS/CZ8JddIcbvk X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR12MB6648 On Fri Aug 7, 2026 at 5:17 PM EDT, Kairui Song via B4 Relay wrote: > From: Kairui Song > > The restriction that swapcache folios can only be uniformly split to > order 0 dates back to when the swap cache was managed via address_space > mapping (swap_address_space). The old split loop only created order-0 > sub-folios with a fixed stride, so non-uniform split and non-zero order > were rightfully blocked. > > After the swap cache switched to swap table under a cluster lock, > __swap_cache_replace_folio already gained the ability to replace any > number of entries for any sub-folio size in one cluster, and the old > swap_address_space locking and limit was removed. The restriction > became obsolete but persisted through multiple refactorings. > > Drop it now: swapcache folios can be split to any supported order with > either uniform or non-uniform split, except order-1 which is not > supported for anon folios. Mappingless swap cache folios could be either > anon or shmem, so for now we just simply forbid order-1 for all swapcache= . > > Signed-off-by: Kairui Song > --- > mm/huge_memory.c | 32 +++++++++++++------------------- > 1 file changed, 13 insertions(+), 19 deletions(-) > LGTM. BTW, __split_huge_page_to_list_to_order()'s comment also needs an update about splitting to order-1 folios. Acked-by: Zi Yan --=20 Best Regards, Yan, Zi