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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?WuFT3Vs04UC3Kv64DQrT/4VUUdow36lPgujvrHpWZ2ib1xwQ+Ry3Xii5xIE7?= =?us-ascii?Q?zVTxSo0Yk8oiSAAOuBI2ptzfxCkNWsPaoUpuV9eNpN9ROpHf0pJcKkoUSny5?= =?us-ascii?Q?lnXrTnEqDKjuYKZdsIY0NPjyrn83LXVY1MDftL62CBdXQFR9A4zrXHAX59eQ?= =?us-ascii?Q?Xz0P9SGFAEWv5EcawIMWzjnBqH3+bgx3AsYni8VvXnq5HxGDGUminC4LH288?= =?us-ascii?Q?MpyxTPyCJfFQ20CxNDaTKXEipQDXVgK5k0PdWCQ8gAg3YqN0k/raES+um/5O?= =?us-ascii?Q?BZqHEkrKgezehucfeeTWEHIc/DWvzubqmKWwXLThizaz/vNUut0TNStncMyL?= =?us-ascii?Q?i+w+MRtN6P+c7jCqvHGDGPLJq0Yt+8Ck59pBfJEGw7g4UgMNi17B3HCvedvS?= =?us-ascii?Q?angX8wJcWejgI9k3b2WQ3bNsAVQ6HegDiMmD1hwn6EgTahrfjcI3QmLs1TxW?= =?us-ascii?Q?H7TS09rw8vDr/wfDpmQu5NRfY9ztUaVipu4vYKJYi83JXG4euYSDpLaCshhR?= =?us-ascii?Q?hvZRIgu5VDvQjzLmkk5+2qRflAxJHvDvGPlNS31TzvgPaEuqGWt42dkwSu7+?= =?us-ascii?Q?R/WE7rSGJI24hNG6es3T9b/LcLXMv+3eivwe6ILltlBChIgMVnFzmDi7Khnx?= =?us-ascii?Q?VxNixVRGiOvn5OXXM5au0jaZSdA68sWQy0E/vNCZw/qI/XLvKsTpBPKh44Vf?= =?us-ascii?Q?fdYS2KYU4BY8CeiiffVYJamGcBcf2/iB6FNt9qfeKK//CMin2QtdV8j9INc/?= =?us-ascii?Q?Kv3bLwlxh7b6z+5VqZ9Gyb0VcfF9ZaTJHu3RXGCxporeLg0vkVoKw7yje0eu?= =?us-ascii?Q?Y/+hEkm466rofUXBQ3jhWlIBgJD7ha4n7eWyd5iKi8DMwJ88/2ldYMr0rYE5?= =?us-ascii?Q?r/H74C75b+YNGC32IuPNETF+VReRPd58REu1VuNwJaB3D3sW/iJPHXyydobV?= =?us-ascii?Q?n0bJKG1tVFvRQln6kFmfO8LbMqQX3ZHaIM/OrStGdxHsazUGvQDRsgjNRSyt?= =?us-ascii?Q?9WFSjEnTV26NaPUj+VHzOs6xm6HYWzR5Q9caoC6VHSeUaF0ivxToTsiuHCRs?= =?us-ascii?Q?j+Z4/bfSMzztNNSfl8jynsKcwvwAwWesqonQ60VW4mI00ddaqq0vhLpDUPrc?= =?us-ascii?Q?mfpApAXnYltqO2NpSvtxoeNwXf8CwsVFnwCeQlUD7H/QObwQmFGYTKa9Qj9d?= =?us-ascii?Q?VrODLvFIRB4sIT+RTTnHUj2O8qqkM1zLISMvs9S0lwpnUpa42WLP6nVf20+z?= =?us-ascii?Q?NViC9V2Hj0PSIJKFqTeb7ebO7//sm6vAerMzVDGdJSYpD8rrqe+NIykpgroi?= =?us-ascii?Q?3sf7+lL08+MsQ4xQ7N4gDFtqD2FTyrnuMFoWc8oKvXSQOafWuvIgByOba7YN?= =?us-ascii?Q?eQDAcB4OhlLLnkgihVVXkUHfRE1NlJlyiIKzHdzPxIM9TdmCgRAPi26gjQXX?= =?us-ascii?Q?EhC1vxVjwyGgtgZYZWJFXRiGcAUPj5AONJ5Dejg4DXx0N4xvG8k6sbbvMmRj?= =?us-ascii?Q?j3oZFTmI+pzqNslIraDC94QL99r/LH3dole1Cs1FbbQxbeTy61zx/HKxvUfq?= =?us-ascii?Q?eIq1SNwKBrTTxUR9qv1+1SICOkaS9pKfLa37aLl/4WrAtgVzrsfL0nlEeVYp?= =?us-ascii?Q?Pszh69PmKIhR2CWaQx6Lbm/foGWzFzi8hQXpGckkLLYJzyqjW1on2r9En4jO?= =?us-ascii?Q?1T/Y1OSY53ppl/PpcbXE7PelNq1svq2ZDVuzKMNCvky10WsXf9o2oz94KpHu?= =?us-ascii?Q?EPaVp+WB7w=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 4f00ee21-b494-49d3-ae52-08df34597884 X-MS-Exchange-CrossTenant-AuthSource: IA0PR12MB8374.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Oct 2026 18:38:19.0108 (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: uJxf06Y63HrdcD+RLJSRMEoVTEDlwZQD0O2LWpRjZJXvZZFoukZokDANAr6fuB/z X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB9498 On 27 Oct 2026, at 11:46, Vlastimil Babka (SUSE) wrote: > From: Josef Bacik > > free_pages_nolock() and free_frozen_pages_nolock() put the page on > zone->trylock_free_pages if they get neither the pcp lock nor zone->lock. > add_page_to_zone_llist() keeps the order of the page in page->private. > The next free_one_page() which does get zone->lock passes these pages to > split_large_buddy() with ->private still set. > > __free_one_page() writes ->private of the head of the resulting free page > only. If the deferred page is merged with its lower buddy, it becomes a > tail of that free page and keeps the order in ->private. > > All other free pages which are not the head of a buddy have a ->private > of zero, and since commit 819bfbd47e49 ("mm/page_alloc: remove > set_page_private() in prep_compound_tail()") the allocator relies on it. > When the stale page is allocated again as a tail of a larger page: > > - prep_compound_tail() hits VM_WARN_ON_ONCE(tail->private); > - with the page checks enabled, __free_pages_prepare() reports > "BUG: Bad page state", "nonzero private", and leaks the whole page; > - without them the value is seen by whoever uses that page next, e.g. as > folio->private of a folio which is split off a large folio. > > Only pages of an order above zero are affected. Those can be freed > through _nolock() by the stack depot (order 2) and by SLUB (a new slab > which cannot be added to the partial list by kmalloc_nolock()). > > Clear ->private when the page is taken off the list. > > Fixes: 8c57b687e833 ("mm, bpf: Introduce free_pages_nolock()") > Cc: > Assisted-by: LLM > Signed-off-by: Josef Bacik > Signed-off-by: David Hildenbrand (Arm) > Signed-off-by: Vlastimil Babka (SUSE) > --- > mm/page_alloc.c | 2 ++ > 1 file changed, 2 insertions(+) > Makes sense. Reviewed-by: Zi Yan Best Regards, Yan, Zi