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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Ralph Campbell , Matthew Brost , Francois Dugast References: <20250908000448.180088-1-balbirs@nvidia.com> <20250908000448.180088-7-balbirs@nvidia.com> Content-Language: en-US From: Balbir Singh In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: BYAPR07CA0038.namprd07.prod.outlook.com (2603:10b6:a03:60::15) To PH8PR12MB7277.namprd12.prod.outlook.com (2603:10b6:510:223::13) 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: PH8PR12MB7277:EE_|DS7PR12MB8420:EE_ X-MS-Office365-Filtering-Correlation-Id: 828fa678-fc83-4a3c-31c9-08ddf1b9eb10 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|10070799003|1800799024|7416014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?SFQ0aFcyKyt1enlsamxDc3NwdEM2Vi9BZUJ2OGlBMGpqcmJLRmc5T1VHeHMy?= =?utf-8?B?Y2NabG54Y3g1UkphL3E0bVNFNnNON2liSDRPdXBPUStoTGIzZzNBVm5pcWxw?= =?utf-8?B?dlJVeUVuZjRoRkRmSnUzNlZRV3lPNU42RXViaGJ2N1dFSEJoWEhkM2M2ZFpE?= =?utf-8?B?eWwrMUlKV3JlVUR4Ym9mdHpLdU8yU3NNMzZMZVlzd2g0Wklhc2VlbHJxU0RQ?= =?utf-8?B?eStYNWZDcDZFOU42NzVEZ0RleU8vSFVNazBQMElIZjZKOXU2N2ROdXZvYjJW?= =?utf-8?B?WTc4V3hyZHBJYTV2T09nbGZpeXY3VFVvVTdCRllocU5Mb3p1VGJVMDJQeEs2?= =?utf-8?B?Z2lOMlE0OXo3LzhIbFdwSWwraHI5VDMvTzE4Ty9vRmRhRTJoR1gyZkpXS3Zq?= =?utf-8?B?OXFjRmlHWGFKTm5ocWJxTjZ2SkFFMm16S2hUZHBSYlhOUHhRQ251dERwTTRB?= =?utf-8?B?cVNHNUxaQStQaWUrL09PNHhSSUpObWdzekFVUWY3dXJmMTNld09mdFcxd3Jr?= =?utf-8?B?a2EwZXJlSjd5dUlpM2RxeEVzeUY1MWM3eDZ2MEZ0b090ZGprT0ZWVlFHUWZh?= =?utf-8?B?a0dqSkRSRHphRVk5V1ZHV0RoOGRXRk5Dem5PSldqSFN5ejFibUdUUVJ1YjIy?= =?utf-8?B?enJsQzZmZGV5T2lFVGJYQWJGS0dLS1Yva0RueUt6clBKSDhnVzBIWjc1SkVJ?= =?utf-8?B?cHl2QlBjaEFrdXNwUVg1NUxwY1cyVkZ3YWxUU3RVaHdHUWp3NjBiZCtqdWE5?= =?utf-8?B?UmNVVlM3amRXMXNTeUtmdjEvRmJyZ0xuMmdmaWd0ZDM2YjM4cUQ5Tll1NCtM?= =?utf-8?B?NlE2OFdkQXFzRGNUbWFNaEhKMmxwYUU0dHNiVEpndHFiT0FPcVJhUElQYmtJ?= =?utf-8?B?RytjUlRzVjE3RjAxRitDNHlFWHhwcm9ndGdSQkRNaXFpek1TQ2FJVlVmQWIv?= =?utf-8?B?TklUaE9sNTNoMlhVZitYcndpTUtzNWE0cnNHMjFUMDY4NTZtL2JxMlgrMWxs?= =?utf-8?B?MEkwdmUza01TTVVYSGpOU1M4RS9tU3hhZVBwYzVDUVN0aHNZMzFXNnVkWTNN?= =?utf-8?B?YlI5dmx2SzNvWU51UFZ3S1lzZkFDMGpwVEJyTVNFR2loNnB1VUtBZzZpSENz?= =?utf-8?B?LzRTNDBWWUpZVCsvRllSK3k1bXBhcmh3RnBYSWJkSTM4RSs3c0tmMXZZVEhZ?= =?utf-8?B?WWZrMnM2REJkdy9KSUtCNXp1SUEvSWZhc0k1ZW1RSEFoWmxJRGpGdmRKOTNz?= =?utf-8?B?bmdLYzFYZEpFdEc5Szc0czRoeERiczI1Y1BkWDBYRXkzVzVPaEV2a3pnd3VK?= =?utf-8?B?TjA2ZXJxQXhxb1dsZi92UEJZWHIrRDNETjZIV1hHaTB5Ui9odDZhdVVySlB2?= =?utf-8?B?YWtUa2JtZFV0STdUclpwaC9FM3lUVDFRQ2U4ZE5XYTFBZUxQbnAxcmQ0dG1C?= =?utf-8?B?QVVJQ1VpRGlNRUJnNXFJZ0JXMEJZWHptQ0N1clNKMU0zMXRoaEVLcG5iaDho?= =?utf-8?B?LzMwclBndEwwNXIwUDIwYjlXV3hKV0dNOC9GVGJmUjlhcC9Tb2M0R3p5U0JC?= =?utf-8?B?ZitoOHdVMkxhczB2SHJINjFoRVEwVnFmSzdRRGc1dTltV1ZiS3llNGlSQ2xp?= =?utf-8?B?NktUR0pDMTZBd1ovbGxka3BQNzZxczhhL1JoYkEvdDY1ZU5SOUpRK2M2cXR3?= =?utf-8?B?a1AvdUVJOUdYRkNqUTVOSVU0VnNrQWVxaTZDbWNCVnpPZkZGYlQ1dDNtVCs3?= =?utf-8?B?a3pYTndQcE13djhCcjBvTDd5NWV5ZTVMN2k1ekw1YlYyeFFLTDZkcHFCU25S?= =?utf-8?B?UXlUejc3UlRRWHliSEZRMm9RK0FqSW5KVmQvY0xkTlFXUWloV1hyVFU4U0tM?= =?utf-8?B?N3lFS2VLSDNWSm5yRkJkUXBLNWtvNDdlSUhiK29MK0hUQk9mQk9adWQ3OVh2?= =?utf-8?Q?7C6eWgklyNk=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH8PR12MB7277.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(366016)(10070799003)(1800799024)(7416014);DIR:OUT;SFP:1101; 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When a compound page is passed, >> the first entry has the PFN along with MIGRATE_PFN_COMPOUND >> and other flags set (MIGRATE_PFN_MIGRATE, MIGRATE_PFN_VALID), the >> remaining entries (HPAGE_PMD_NR - 1) are filled with 0's. This >> representation allows for the compound page to be split into smaller >> page sizes. >> >> migrate_vma_collect_hole(), migrate_vma_collect_pmd() are now THP >> page aware. Two new helper functions migrate_vma_collect_huge_pmd() >> and migrate_vma_insert_huge_pmd_page() have been added. >> >> migrate_vma_collect_huge_pmd() can collect THP pages, but if for >> some reason this fails, there is fallback support to split the folio >> and migrate it. >> >> migrate_vma_insert_huge_pmd_page() closely follows the logic of >> migrate_vma_insert_page() >> >> Support for splitting pages as needed for migration will follow in >> later patches in this series. >> >> Cc: Andrew Morton >> Cc: David Hildenbrand >> Cc: Zi Yan >> Cc: Joshua Hahn >> Cc: Rakie Kim >> Cc: Byungchul Park >> Cc: Gregory Price >> Cc: Ying Huang >> Cc: Alistair Popple >> Cc: Oscar Salvador >> Cc: Lorenzo Stoakes >> Cc: Baolin Wang >> Cc: "Liam R. Howlett" >> Cc: Nico Pache >> Cc: Ryan Roberts >> Cc: Dev Jain >> Cc: Barry Song >> Cc: Lyude Paul >> Cc: Danilo Krummrich >> Cc: David Airlie >> Cc: Simona Vetter >> Cc: Ralph Campbell >> Cc: Mika Penttilä >> Cc: Matthew Brost >> Cc: Francois Dugast >> >> Signed-off-by: Balbir Singh >> --- >> include/linux/migrate.h | 2 + >> mm/migrate_device.c | 456 ++++++++++++++++++++++++++++++++++------ >> 2 files changed, 395 insertions(+), 63 deletions(-) >> >> diff --git a/include/linux/migrate.h b/include/linux/migrate.h >> index 1f0ac122c3bf..41b4cc05a450 100644 >> --- a/include/linux/migrate.h >> +++ b/include/linux/migrate.h >> @@ -125,6 +125,7 @@ static inline int migrate_misplaced_folio(struct folio *folio, int node) >> #define MIGRATE_PFN_VALID (1UL << 0) >> #define MIGRATE_PFN_MIGRATE (1UL << 1) >> #define MIGRATE_PFN_WRITE (1UL << 3) >> +#define MIGRATE_PFN_COMPOUND (1UL << 4) >> #define MIGRATE_PFN_SHIFT 6 >> >> static inline struct page *migrate_pfn_to_page(unsigned long mpfn) >> @@ -143,6 +144,7 @@ enum migrate_vma_direction { >> MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, >> MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, >> MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, >> + MIGRATE_VMA_SELECT_COMPOUND = 1 << 3, >> }; >> >> struct migrate_vma { >> diff --git a/mm/migrate_device.c b/mm/migrate_device.c >> index f45ef182287d..1dfcf4799ea5 100644 >> --- a/mm/migrate_device.c >> +++ b/mm/migrate_device.c >> @@ -14,6 +14,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include "internal.h" >> >> @@ -44,6 +45,23 @@ static int migrate_vma_collect_hole(unsigned long start, >> if (!vma_is_anonymous(walk->vma)) >> return migrate_vma_collect_skip(start, end, walk); >> >> + if (thp_migration_supported() && >> + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && >> + (IS_ALIGNED(start, HPAGE_PMD_SIZE) && >> + IS_ALIGNED(end, HPAGE_PMD_SIZE))) { >> + migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE | >> + MIGRATE_PFN_COMPOUND; >> + migrate->dst[migrate->npages] = 0; >> + migrate->npages++; >> + migrate->cpages++; >> + >> + /* >> + * Collect the remaining entries as holes, in case we >> + * need to split later >> + */ >> + return migrate_vma_collect_skip(start + PAGE_SIZE, end, walk); >> + } >> + > > seems you have to split_huge_pmd() for the huge zero page here in case > of !thp_migration_supported() afaics > Not really, if pfn is 0, we do a vm_insert_page (please see if (!page) line 1107) and folio handling in migrate_vma_finalize line 1284 Thanks, Balbir