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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , , Subject: Re: [PATCH 2/4] mm/huge_memory: move to next folio after folio_split() succeeds. 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ek9lagwdS8kmbvtkbo+jJvdU8a82+4wSQCGhignsJiyi4QIbSvou1ikPOCbJ?= =?us-ascii?Q?jEgssU3FLhMn8SymU2KGH9UHhh98suAgTd/vTtJteSd+XAi6N0S+y6b2wxwD?= =?us-ascii?Q?jeEtfJ6py80Ql1i7nU5ng23y4BiHa6S3Hs6wzak588yo0n+fMa7EdShjGRkU?= =?us-ascii?Q?Gc28kXWtStZbSmjTuhQYoLjJtCO11mc1/ZgzS8K7KO6pcKB1PIWCqLqCqdCN?= =?us-ascii?Q?LnnezBxvVe9tRZodxn0UH0A4a6YXgadZUoYxy1a2G5YQpyNA8Z9B6XMGxKVJ?= =?us-ascii?Q?Gt7EYQrqUNrthQMOn3mjz4Ko8sdVRTVdAMu+/2THkcxugvmettAz396zPBc1?= =?us-ascii?Q?eJ26RMhSMLnkmr6XVBqXVtIk3+6QbYwEJBvoiRX5DndnBDLpPRfrZxfDrVoK?= =?us-ascii?Q?52f+sfcfSG1/mP6KUKg3BQwWNbr1lOS4yn0wnSJQOhJpzcOV5KcDq5/t6ys0?= =?us-ascii?Q?tLe4DdZC3WaDZV4cvuqZmtrGoKnlL5Craqqz+i6xM/dfbhOdP5yF8gJcX/5w?= =?us-ascii?Q?y7V7k7F3NevtHnQfOWInK0gNtLivDngjXGR9CxczSK74Jt1nh47UrhqyAecT?= =?us-ascii?Q?Ge6q1JJTAOd2Tm6u+YpYFVenlFtYRAUnoyAp5R7sT7Z8NGWEn/XOQgCko5P1?= =?us-ascii?Q?0PsubcNup8UIsR5Qmy7MV0Kl6RbTsacWi2jnjMlf5cM+fEOnH6IWUPuj4CUU?= =?us-ascii?Q?1LTMgR4FcOTwaM1V7lDN7PiUG8YIsxxkJ/7f6wHftmxeOAhsXOE51kmCXMCC?= =?us-ascii?Q?iMtGOtyUZm9iN9TkVbx3mhSV5Ucoe7t0/QUIDbbPEweg3mdxxPCuVTntR1e3?= =?us-ascii?Q?H6gRtcTFjhgWYdZeh54MIXmc1K+WRr6laikzOo8G17fB3sDEPXAHBzgaPcdV?= =?us-ascii?Q?flkX6xToeLMXYayBxBpW4sLkyQgsPwBMJry8a92CJ524Hgiw03nsgakoxMk5?= =?us-ascii?Q?hTci6X7oabs9Ulx3siT3vcc6bGThrxgWnx9orGXCSw89d2FpN0B1hieq9nj6?= =?us-ascii?Q?IQVu/WbzdXMDC6IiS+W1kKzrxjiuJqOVs01yGz8/mnYn4gIAq6VVdQVwzR+4?= =?us-ascii?Q?1fKamH+glkB+sxLChwFeHOOAP5cTxUkYfxeL3YJklqp2ghoksbXYksonqw0a?= =?us-ascii?Q?5b6xacdvLpHFIBV/VnCDrsoEK96BWaNwJ4Z1qBaXjbH1+T5GTKUAQZW6fZVs?= =?us-ascii?Q?BRs8Z44P8OEvwcuezXQR4s1maOsfM3urM6CnEOgyA+4V83jE7XlOEvp5547x?= =?us-ascii?Q?eJD/i+dWxcHgp09XYHY9QqQtlhF2Y02iL8rwCM+WYPa0jsXSYjZqHG++lL62?= =?us-ascii?Q?DBS5GzAS7ulRMNlDU5gSN5VseIIrBKhLPdKuHZ9US6Op5s5jxuIxuTfApCdj?= =?us-ascii?Q?Er4gOW6XmRwCMXWA4hfFHsa8kpFlSMi3/4KDiDtdwJMV3LgagqxtRuBLfEMz?= =?us-ascii?Q?JD+Gk11+jWMT7dpH+m49LSrbaAqhvrL5xO1M4HoWH2L81vk7HW9ITX2LZW0W?= =?us-ascii?Q?rj3/pxc90t0L5MG4r8ED7TKK95rKGNnWYtHY7Go7W0EW1l7sn+2wNdIddlYe?= =?us-ascii?Q?EduJP4tjH/PsO/eoR9wfN+tpL0xjMFseb98s5O4V?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f5f1a17d-e187-4ea3-a55e-08ddd69266e3 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Aug 2025 15:44:03.7519 (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: pk5CKqok4iY4XfFOc9ZuFumyb+2Acyh7WtwjYwZC72gYlL824i/5elgWI23q8lXY X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8088 On 8 Aug 2025, at 11:24, Zi Yan wrote: > On 7 Aug 2025, at 23:15, Wei Yang wrote: > >> On Thu, Aug 07, 2025 at 01:05:09PM -0400, Zi Yan wrote: >>> On 7 Aug 2025, at 4:55, Wei Yang wrote: >>> >>>> On Tue, Aug 05, 2025 at 10:20:43PM -0400, Zi Yan wrote: >>>> [...] >>>>> >>>>> - if (in_folio_offset < 0 || >>>>> - in_folio_offset >= folio_nr_pages(folio)) { >>>>> + if (in_folio_offset < 0 || in_folio_offset >= nr_pages) { >>>>> if (!split_folio_to_order(folio, target_order)) >>>>> split++; >>>>> } else { >>>>> - struct page *split_at = folio_page(folio, >>>>> - in_folio_offset); >>>>> - if (!folio_split(folio, target_order, split_at, NULL)) >>>>> + struct page *split_at = >>>>> + folio_page(folio, in_folio_offset); >>>>> + if (!folio_split(folio, target_order, split_at, NULL)) { >>>>> split++; >>>>> + addr += PAGE_SIZE * nr_pages; >>>>> + } >>>> >>>> Are we sure addr points to the folio start? >>> >>> David pointed it out. Will use addr += PAGE_SIZE * (nr_pages - 1). >>> >> >> No, let me be more clear. I am talking about the addr in next iteration. I am >> talking about the addr in this round. >> >> For an addr in the middle of 2M, we still could get the large folio if my >> understanding is correct. Then (addr + whole folio size) seems wrong. >> >> addr >> | >> v >> +-------------------+ >> | | >> +-------------------+ >> >> Not sure this would be the case. > > Got it. addr should be aligned up to PAGE_SIZE * nr_pages to get to the next > folio. Thanks. On a second thought, this new stepping would mess up with PTE-mapped folio split. I will drop this patch (pr_debug part will be moved to Patch 1) and change split_huge_page_test.c instead. -- Best Regards, Yan, Zi