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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 DS0PR12MB8478.namprd12.prod.outlook.com (2603:10b6:8:15a::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.592.8; Tue, 3 Nov 2026 16:12:55 +0000 Received: from IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16]) by IA0PR12MB8374.namprd12.prod.outlook.com ([fe80::d85f:4c87:ae84:3f16%6]) with mapi id 15.21.0569.011; Tue, 3 Nov 2026 16:12:55 +0000 From: Zi Yan To: "Vlastimil Babka (SUSE)" Cc: "Gregory Price (Meta)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, david@kernel.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, osalvador@suse.de, muchun.song@linux.dev, iamjoonsoo.kim@lge.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: Re: [PATCH 4/6] mm/page_alloc: don't undo another isolation in alloc_contig_range Date: Tue, 03 Nov 2026 11:12:52 -0500 X-Mailer: MailMate (3.0r7038) Message-ID: In-Reply-To: <6091a4d5-ded8-423e-a806-2c4b11f21e09@kernel.org> References: <20261027042204.3741307-1-gourry@gourry.net> <20261027042204.3741307-5-gourry@gourry.net> <6091a4d5-ded8-423e-a806-2c4b11f21e09@kernel.org> Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-MS-Reactions: disallow X-ClientProxiedBy: BN9PR03CA0069.namprd03.prod.outlook.com (2603:10b6:408:fc::14) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|DS0PR12MB8478:EE_ X-MS-Office365-Filtering-Correlation-Id: 4656f0a4-0907-4233-4cb5-08df39c55158 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|7416014|1800799024|366016|4143699003|11063799006|56012099006|261009223027099003|261022105027099003|261102123227099003|261021121427099003|261028144727099003|261026140227099003|261026121527099003|10067099003|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?bRDdnvkIm3P9iRNO2GcLAcWuFayHfgmYtI9V9ThTUTaJay8A4NNDKp69yeLM?= =?us-ascii?Q?VMrbNFxENH7Y4LYKmSXyOZBLGIFHqtpOVwuUu9MscSzhESKkVSqHstgekl89?= =?us-ascii?Q?9h80Uzk1jmx0Q0upbTqmGN+a+LWN8xesflIeGifPDSIS5a228WceiEiZikC1?= =?us-ascii?Q?hgQuR2anUHhgDr1EkR8xDDzLLUrj8OgbMVO8OaD7Mh1Z8Jvbq5XZkTgOLcmp?= =?us-ascii?Q?wv53Uiw/aspjouuzqf/4x0Z7aMIc/vXKk+NQOcgP5m6tbhMbL446gXVSqLyi?= =?us-ascii?Q?GAX0p00iAoO1k2j42wHhoUuPVUJHN4IIMVa8u2vLkwnMqAM6W5kYFvDcwhtK?= =?us-ascii?Q?kwiPP1HjUBNrEMAJdlTc4ByToqKtjSa2DsdjTueC5976bkKAGHOspRCMKmra?= =?us-ascii?Q?Y6zRiEZfpjzni/GEoVMXk2WPGhYBhNPc8FDeGi8xmtjf6SN5vak6wGVXIRhk?= =?us-ascii?Q?+EzqkKWvFJHwnXWBFg6lkrtwxU+vnFha8o7jueAx4sIkDbyezhMYUJZmk6eS?= =?us-ascii?Q?p44UEMU2ADJuIwFOT/BcRu7yuKx8uJglU6cLzGO7LDCEBi/pHE2wf2eU6GXC?= =?us-ascii?Q?iDAIKQCgpqIMghwUfYFXB2nr9yKjTtm0qStg7nFCAIWgktHQhDhfOzSdoPVl?= =?us-ascii?Q?SOYxCD5TxkYrbL8oJ5CpjLlsiOL2m1yJL5Yv3RnIbYZMkCSl18eXMQHSzeHB?= =?us-ascii?Q?5jC5NIeCbX6wYJNZFwqndlW0AAbsTopO6KvdMrLie0HqOG1STo2A9edsriNn?= =?us-ascii?Q?o1dIQGnQHebunYy2v2r7CBAXAtRqbqXPdA9eY4v7iEAsl79xeJVlyCpWmGdI?= =?us-ascii?Q?OQQOmWcJXl0FnrsjWPkuvLrhcWD8Rht1PtGd4hm0BwWSl6zVam37mmvlgiGh?= =?us-ascii?Q?7kgMvCHN6hxiJWFYu6gtpmHSTeQqlkeeEGkHCYJLu6ig/sVoAwlnn0Qwgwfq?= =?us-ascii?Q?TR2fyY59BTfftceEzGy5JcXcc2UtJh0sUJxrdaxSW4q+tmebEPNjJaORj4M5?= =?us-ascii?Q?5WFz7kptU2KqI/7uoKnFSoPEoYowsMV3JAwV9Q0vkJo9HgGp/6avZQW1o4EK?= =?us-ascii?Q?f+8Mq+QK9SGplEn5W1/dcqWBGe1VShRN8PqNSBr/mXJ0QPp+fWxJlSecQLk4?= =?us-ascii?Q?31l0a2FaGOm1XijZRw0LgCONboNE2hJPVC433vnE1R69NQhN/J5uY6Hh4qIb?= =?us-ascii?Q?nbt8JgSx6Huxf9T9BW4UeFC/owfqUf/ZfanwkBO2OaTtR+Z2GLs9JuU5ReGG?= =?us-ascii?Q?cYjz6KWGkEdJPSupNqY0zwDM5B/LPNW+ZpvBxRCPlREkIyHoOsYevfErSpHH?= =?us-ascii?Q?IP/pB5zkgXhBj9aupgcw34Flhjbt2C2kVZ0HaQGgFPSyp7V+p9CWnfLk86hA?= =?us-ascii?Q?bdoj1DtYHxqfBEsoWXYO0ngTdcVPSgqRjLLXzy+U/bv1B8hdvlJF7UC4Npy3?= =?us-ascii?Q?3nWhCnT5IYDx9pE/AhZxAFtoMGDHuSv/O0gysSDkwL51BRUwszXriKaSdvY0?= =?us-ascii?Q?hiWaCofXWF5wK+pdQvoKiZVVnukq2ocbQ74y3Yxfd2EZj2oLmbpuSZWZYco0?= =?us-ascii?Q?FHxo2sr9KyXx4j/zGhjBCCfnlNpOogevPr9KQKmIBh5mCmcBqD68Ton1b8RF?= =?us-ascii?Q?KPb9kTUbhbF0SxQaG75j0yK2w8CaXBK8gz/P+D7i0wQzQ2Sf0ZiIJVnTRXyd?= =?us-ascii?Q?/1s7935IkiorZnu2dJ5m7up8rYoU2gVwzct36dSZL2R10WWr?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 4656f0a4-0907-4233-4cb5-08df39c55158 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Nov 2026 16:12:54.8050 (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: AuZ8oyWeWDYNkq05fnUFwrpDEuvDc1YRaPCNFNxfN9fJsz6OSAmzxAxCPCcaRfO9 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8478 On 3 Nov 2026, at 10:12, Vlastimil Babka (SUSE) wrote: > On 10/27/26 05:22, Gregory Price (Meta) wrote: >> An alloc_contig_range() that overlaps a block going offline can leave >> the offline spinning until it gets a signal, holding the device hotplu= g >> lock. When isolation fails, alloc_contig_frozen_range() undoes it ove= r >> the whole range, clearing the offline's MIGRATE_ISOLATE too: >> >> CPU 1 (offline_pages) CPU 2 (alloc_contig_range) >> start_isolate_page_range() >> blocks are MIGRATE_ISOLATE >> start_isolate_page_range() >> -EBUSY on CPU 1's blocks >> undo_isolate_page_range() >> blocks are MIGRATE_MOVABLE >> test_pages_isolated() >> never succeeds again >> >> start_isolate_page_range() fails only on a block someone else isolated= , >> after undoing its own, so this undo only ever clears another caller's.= >> Return directly, as before alloc_contig_range() went pageblock granula= r. >> >> With offline_pages() parked after isolating a DIMM block and a 1G >> hugetlb allocation made over it, the offline on base still loops 30s >> later in 4 of 4 runs: >> >> offline_pages+0x5b2/0x1570 >> memory_subsys_offline+0x17e/0x470 >> device_offline+0x250/0x340 >> state_store+0x88/0x110 >> >> With this patch the allocation still fails, and the offline completes = in >> 3 of 3 runs. >> >> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock gr= anularity") >> Cc: stable@vger.kernel.org >> Signed-off-by: Gregory Price (Meta) > > I've applied this single patch to page_alloc/for-next-fixes and will dr= op > the version from Josef [1]. Also transferred Zi's R-b since it's the sa= me > code change (plus comment). > > [1] > https://lore.kernel.org/all/20261027-pgalloc-ai-hotfixes-v1-1-9c7d1aca8= 01e@kernel.org/ Thanks. Best Regards, Yan, Zi