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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?N3fHmI4jc/D9+zZ3t4CHQv8UEBSyasoFKkAxQTo39qaCIYItRyZrC53QM4zu?= =?us-ascii?Q?uEUU43ji58gp105mB/Guzv68ryJlW/ZFoQFczt5ejYSU8T+0UmZPtabj8NXs?= =?us-ascii?Q?ti0DwSB4C+w8H0tNctS0DH0BpQ/tfZ5RQ7TPo/k42x6i6QDgyZTBCTo5lyTC?= =?us-ascii?Q?wnJeTTUqqkevhir4M4V/2d2WdqIOM+2eNejGInOQdZFWFWHWyEUg2oshJCm8?= =?us-ascii?Q?8Bj1dLrtbknRg99hqglbwd+NzKcQbEKkhSR9mYzOi+0KDzQDrafkySIlZ6tI?= =?us-ascii?Q?ImWqsiah20FGZiDbjQfvxj3yp5V4piRbAU6uLoKvu8SMw5i2AgZ3txRVku0G?= =?us-ascii?Q?aDLvxo8XMHUKmB0LiKIIYN5kvlwEHBpSfIghR7DwhWhjw0qAEiwBO09Z3RQl?= =?us-ascii?Q?al89TEdJpQawtObvsvcpjARGCZSFFemaF4lsi8D/3JBMX4j7Oq4wyu88glO+?= =?us-ascii?Q?y6OC27OE/n73wqs/7Q/MtwRVz2wbHwrJ/XeXJSNrG8jh8FugZCuoqkkeo+dn?= =?us-ascii?Q?gcPdF7cJ/jXovWyic+1ojCfMuR7bnYIwXuVTgmKqzTpxrj2ZYzNyWrDe/ZKW?= =?us-ascii?Q?NQwup38CoeMtSB4F8CTERIORr2uQ2hYkxoCSO/XXYmVUR/5YUfKhfI8MVQEM?= =?us-ascii?Q?GDPWyYR5UMR81kQe68hrUm+tmOWbJ6ANOawFNbqTpcxTcDcB6ZBaDBQD0JvB?= =?us-ascii?Q?ibAxM1xFBIPmmdjLtGm6VXtejMJxbTLQOP4C1UO9TdTaxgxaf/uN/TSk7Vm3?= =?us-ascii?Q?UtfVgo9Ta/0uJxJNvQmpOnm/Lt3AL+/0XRdSEFco5cDhVTuLvarA+uXqloRq?= =?us-ascii?Q?QUN2CuYhufWboFCmBJREoi1JznANbSHMu/JONri0OFCbgPDsIgd1UCgX0V3P?= =?us-ascii?Q?DziQgYoVtEFPIXEIMwNZq1tz+hqjZbW82gqCgjirfH4vzgsO0vkv8CGL0Sf7?= =?us-ascii?Q?3BqWk4njnIocKoNBZsAP7+mQZRKD9BbcqBieXRi/7vzI9qCXDDQY2w/Y10EU?= =?us-ascii?Q?67kOv856rbwaRAdKY0dlMnWtyxGgy7W/eVCUZ0DwCSmB+wdiAkI7Yuxm/bIC?= =?us-ascii?Q?V0V8AxTr6bYhyicoxoHJ9dCgUyqBaatIq76s5mflOkypaeuWsIFBxbQOqfIL?= =?us-ascii?Q?bbhV3fVb85x1fHPRC0/RZOwM2bhiQQeScUkoB39iHDfa83/NkStyQ8wNDnCH?= =?us-ascii?Q?1lCfiu36gFi/H03hQTBmWOpvCnFW2kOBjIUEYnzekGM5bvU01+fDtwFoXZ92?= =?us-ascii?Q?9z8m8f9ZlqOZbgpMJm+Xmgb+QuFJgmpV7JtNW8PsjOyqZ7vdnuvAGNpW4pb/?= =?us-ascii?Q?nyZtqaPQipcGP/bjchjsNwydCNJ3X9gLqozwFcTZIovslcpGP0psBhx8AJA9?= =?us-ascii?Q?m4ZrLyCy4kVFX2uru9025/yqU+8xwPyMVWkgh+Iv6pGN9IJaAf3QmfA4Gb0r?= =?us-ascii?Q?uqY8qlvLzP7j/+cTAwHLjCMZJws4mQ3ij9ahN4UNl4cSvXG8O4uWM2h1/Uiy?= =?us-ascii?Q?jyf48uIu3gTDvB1TQKOHO94S/LYxorrp+WT8j/qshj+uwCwDd4XoTakv8uiD?= =?us-ascii?Q?4YyfhAF87CX8moFLMM+mg3RvPqik9P7wDwyLk3jGQTNzebAcnGrQL1BR651Y?= =?us-ascii?Q?q4YYFo7GuLhcOx0DtBNw0GN6+LT4o40Bb/XqHmCEf+sEQEEIjc+rL5LSiZGU?= =?us-ascii?Q?BBPUCBYTAkxAUUTJtyMNn9fcvHTFkxpb2pKYYHRB6pkow0dAChDii5f4Vjci?= =?us-ascii?Q?PJqbZM01wg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f304f686-4552-40be-8cbc-08dee48e4f19 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4827.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jul 2026 05:35:00.0969 (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: +1dsghOzXbukddXG4Qma1OShAkRBDgFCj2s4JpFsvsgYphiUzMUmQbjDQknYqL7NO+dNEV3fGNhHElcydqEthw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4408 On Fri, Jul 17, 2026 at 06:12:06PM -1000, Tejun Heo wrote: > Hello, Andrea. > > On Fri, Jul 17, 2026 at 11:11:10AM +0200, Andrea Righi wrote: > > I randomly triggered the following with this applied, but it looks unrelated to > > these changes: > ... > > This might be a pre-existent bug, I'll investigate a bit. > > It is pre-existing. Cgroup migration doesn't update p->scx.sched, so a > task moved out of a sub-scheduler's cgroup keeps pointing at it. The > sub-scheduler's disable path only walks its own subtree and misses the > task, and the task ends up holding a dangling pointer once the scheduler > is freed. In your crash, the watchdog read a garbage timeout from the > recycled memory, declared a stall, and the exit propagation then chased > a garbage ->children pointer into scx_claim_exit(). > > Reproducer, on this branch, KASAN reports use-after-free within seconds: > > 1. Run scx_qmap. > 2. Put a CPU hog in cgroup A. > 3. scx_qmap -c /sys/fs/cgroup/A > 4. Move the hog to a different cgroup. > 5. Kill the sub-scheduler. > > I have a fix series which re-homes tasks on cgroup migration in the > works and will post it soon. Oh I see, thanks for the details. About this patch series, everything looks good to me, so: Reviewed-by: Andrea Righi -Andrea