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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Balbir Singh , Matthew Brost , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/6] mm/huge_memory: convert VM_BUG* to VM_WARN* in __folio_split. 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?bBURzPjtHI3XVLo23EzCxmXg1Ke1DcKTsTPQehgkwfWvDn+5rwVsu5wI4D3g?= =?us-ascii?Q?3gs8qcctxTWFEg3CN9aSyBufglOCRIPIL9MLJfW6dbjZHyjXI0TaHYQ73Rqd?= =?us-ascii?Q?QWwyHbuC8WyEb4hmST0AzLSBe4wYYyHd5mipTTP65dlIqiAe9vXeJ7aFCD3U?= =?us-ascii?Q?CFuV0eP2fC+ovq94b1hpRsvONHRrYRF7d9S55B+DcsuYRzucgKz2UpK/ZCY9?= =?us-ascii?Q?DDp2cqe60ReSIhGKuQUgYRxEm3dwuNRMmyM/hX4Q/v0rq3FbbbZNAveEM09F?= =?us-ascii?Q?iIShv/kdGOXa6x2HSuvoRGDLB823HFnB9q0Tg7NGMSJ/C7Fs1mr5SyfgdBrr?= =?us-ascii?Q?rm6crL39qwKlBI/pQ0d104EOV+9/C1bzgApCvgH3wtokRd6uxCDI1sVNaoWS?= =?us-ascii?Q?myZEQlK9Pq9LRtUhL4W1SeVPA6WjK+E44+CpSzvD6PIzOoVrASZpX8OuYkD9?= =?us-ascii?Q?iCXI9RXHMzzPON7CYT6ZUOdh4Hcrceit0Y3v9gmAWQZ1k2CmD7m7OOeXOtUA?= =?us-ascii?Q?PQ8O4Ef/12JWeLG00yxvqpjeG1RE1z8goZvIb3Vf9qSZcdD0GurCEkpuVx7U?= =?us-ascii?Q?D4/qxHCpUYI7WFy2Q8dPBQhMZ7JTaAfFT5iGvj6OdnL7oHJe6Zf+yBJEZ43T?= =?us-ascii?Q?L/uyoiH4K9f0XfKNvEfUtW1pP3KfAQLWhLJttFv3jSJ3rWWVnnWI3huuluSQ?= =?us-ascii?Q?XwZdq7vlGgl5R5MQcD4YaMNaMziCFMnq6j7xTBBCOhe/w8l+hor3ya6k5M0c?= =?us-ascii?Q?kQeiRbFo2QhD5fBfXz6Znf+/xLgidRS3lM/O2rC4uqZyaglu3WMlK4y+4YDn?= =?us-ascii?Q?R1ZecZlO+T+NsRo54NXWGmzRDbHO1JqB/WxWo1GDNdqbQ2sgskmGhpIkxh2i?= =?us-ascii?Q?VYuoXSO6vX/JtkytjjA+Iixu59/MQYMvbhHwqZQpvvxZDgXpgDJkBnrQIiaI?= =?us-ascii?Q?3x61WfJpqzsxT4ZBL4G9QocsdVzMw8V+N/Wv6IvoLRAsNHUCaFUTetEFvzTi?= =?us-ascii?Q?QX1pol7A0dM7KBWx+iSxvytmZce2T3gunNcyO0Sd0uoX/qAADBLTQmJS4d7p?= =?us-ascii?Q?UihpVtrDg5+Fxf6TG8ZUdryCzwqyNKhhRYy11uXbveeccNcgm/YgA/BXojXa?= =?us-ascii?Q?Ua7+FbgvL7N3DSfq/yoreJp1oA9X3WM7IiDVLkQWiVx4S3Oc4+m6hoSzhqDJ?= =?us-ascii?Q?1sd7LK8i24l5zUexEg1FngLUpMwS3HXumFwzzBq89D6xoeEYbo5jeIgEOBT6?= =?us-ascii?Q?EsArSDO+SjilTRUPt/hWFedw6c/eDo03N4vUGnvFTJTklhWz6IaLxevw29vr?= =?us-ascii?Q?5i9jMtyaDYuJsxe+kBggOL0FE5Z65vS+asOzRK49/CpAneZl6Pkja3oX1aKL?= =?us-ascii?Q?YDLXYLwa1X0ClaedqKMZnj7U8cSL2nVL5sVG6p42yqrRhV9u8bw1x2IL7zez?= =?us-ascii?Q?kFadn3E0CND9sBjUVkp8r/jveYim8+bu4wgNiSeMyguMfrRvwtCMqESLs0uK?= =?us-ascii?Q?ZQbazb/4Z9ycCheGeBkmA28CeP0mSCV1TVLGSgXiOD2mT8BiEYqRGQkATprA?= =?us-ascii?Q?Pk9b5VCQF5FRn8XkgyipIzhajg7wFQ4gYJ8jsrg9?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ed621cbe-97c2-4bed-a9a4-08ddc60a395d X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jul 2025 14:48:57.1959 (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: zPJ/1bcyzgKlkUBZfUUaLoqylmMhMdu58d2d0opp/ufaIAvDeSqMHvRm+IlepBGp X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB7474 On 18 Jul 2025, at 3:22, David Hildenbrand wrote: > On 18.07.25 04:29, Zi Yan wrote: >> These VM_BUG* can be handled gracefully without crashing kernel. >> >> Signed-off-by: Zi Yan >> --- >> mm/huge_memory.c | 16 +++++++++++++--- >> 1 file changed, 13 insertions(+), 3 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index d36f7bdaeb38..d6ff5e8c89d7 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -3601,8 +3601,14 @@ static int __folio_split(struct folio *folio, u= nsigned int new_order, >> pgoff_t end; >> bool is_hzp; >> - VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); >> - VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); >> + if (!folio_test_locked(folio)) { >> + VM_WARN_ON_ONCE_FOLIO(1, folio); >> + return -EINVAL; >> + } >> + if (!folio_test_large(folio)) { >> + VM_WARN_ON_ONCE_FOLIO(1, folio); >> + return -EINVAL; >> + } > > For cases that we handle gracefully you usually want to use > > if (WARN_ON_ONCE(..)) Got it. > > because then you get actually notified when that unexpected thing happe= ns. > > I am not really sure if recovery is warranted here: smells like a strai= ght VM_WARN_ON_ONCE_FOLIO() is sufficient, and catching this early during= development that something is extremely off. OK. I will update it to just VM_WARN_ON_ONCE_FOLIO(). Thanks. Best Regards, Yan, Zi