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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?h14c43k/hsKm+vvJE71lGZNdRvOq9Nz3tmQh0pAD7xUj5fyqMjxO/a23el/+?= =?us-ascii?Q?VCmfqPOUTMxexKRxHYEBGlTrinsEr7etUxii0hAa1zDi8MvWwRHCRgz6tX7s?= =?us-ascii?Q?5+TQ++Ah3OQ0/nKSUS57GLggSD46OPPvl7rXs7WuMQQcgWHk9kGYpaKaFmZI?= =?us-ascii?Q?OjexUneIK7vxQjt9JOLomQ4L9fyCAgahiHFzjAYK16ByxZqBOXUkf9yCbm7G?= =?us-ascii?Q?iLXM7JbZeWuO/zVmjPwTDRrSlMekoGVBmYbbIE6HvE6g2U/Tc9C9pzxX+qDg?= =?us-ascii?Q?nQKSwVeTxOge4N0Si3xsB70luKQ3GeR+q0c+hGw2XxVmZa9KI/GUGRvRv/uC?= =?us-ascii?Q?X+tnlRZcmqcvkCp2d4DmGhfj07U0LcRVGmWmxtX0onhvsmEJpMgfSHhKTLW4?= =?us-ascii?Q?8yU8WVS9bikoSljDeo9U/j3dudbdGX3/7IPbQXHyuz8mX56IXvBLgPzoV4D0?= =?us-ascii?Q?iND84ZGHK33elrDAQhLBFEsX/H2Rs+RIv2rOf1WlueaoWVOaLsUSoQ4Vcd2j?= =?us-ascii?Q?TuKYQFkEM23oUzTugmmvBQeiOIiTqeadqBKF9/MhcLC9jSf1V9Ei2t+4fyfE?= =?us-ascii?Q?oofACjmqnQDldiCfZ9PQJ1JjneyvnbJw14gCtrlZlwiibbKS2L6L0qx3oASR?= =?us-ascii?Q?qvlVmig7zbATsYSK9F5gh3FnZqPWqjjVWaRmhbW+W/CVa9glBLhD5SyLF117?= =?us-ascii?Q?HNFuQrJnqVrDDkCiizW3loI/Nl4oVHnIhrKBIFMPRvR8g/BEL+HtV8w4adsC?= =?us-ascii?Q?Pq8YmDNC2VRPfQ04QCgugH2nLAJz5wwAFQaY447eJDla8QxSmDPPGi0qGNG1?= =?us-ascii?Q?y8tr3f6jsFhAhn/MW4RbEh1bntjorzW0kGK2yM3f4L/EvpntbjEkaWNlmhbk?= =?us-ascii?Q?mBa4rCw7zLQ5Ls1TrW3PJxqvRjwoaeEObcMD9r+WIN8xud47yMac1vDGt/mh?= =?us-ascii?Q?cA2+jlmVVLEMXEROTlxCgjIr2Nk4bVQsmOMq1YVOwbKZZlc97TGuUfcnc7jr?= =?us-ascii?Q?fLWr4QoiW5/Pty8UHpyF2U+/kJMOPrIqEt//PcsvN4KdAmGD62Xx5sx8bbQ3?= =?us-ascii?Q?z92Nxbv5qv9KX0ATwCNxbPML0girs7ASf0BcfTw87ytRHLCAhHoxdHgR3QZ7?= =?us-ascii?Q?roMGRdNW4d5z99vlDJ9jCLw3+8Abn95TKeZXq4G2F0LE9xWYmQGFFoBo7IjX?= =?us-ascii?Q?mV5HtlyEWqoN1EJKr2avcTX1/7bFwQgggbLAgdVzu7CxJvlkDNsO3pKCNwx+?= =?us-ascii?Q?nfjp5dh4boQygkGu8SHlQpAUckTAOra1DwaDI/RHK8oqqghShb3SCdC9HDiH?= =?us-ascii?Q?Z74FVZ8brdrmEEZRHCxY+azkr2YD46PWxEweYsSrvM1YzYNJ1zfE6qLOEDK0?= =?us-ascii?Q?YhtJkmCLGA/cgmfp+oogOO12T2N+OZPm09+3w876uHJfn9gEGC6iAbJ5BG3e?= =?us-ascii?Q?R85QSnLJ+Ej0PYJYQBF8wgZ6Xg7I/Cx4OhCgi2sP0roZrQU8zcwM8OVm4Cv5?= =?us-ascii?Q?ZsA6nQgOogMGYp8CIWrDix+EBhLVo0v8Ezg1NvrtKW6jD5u5NQvvgxfPaG7e?= =?us-ascii?Q?n1F6IxBqoOS9XshX/k/CTvbia4fi6qF0edw//dgBbNnaQIwbfDwuLzLJN/bV?= =?us-ascii?Q?LgPpts6YQjNBB01De7/Sfauv8H79JcOpg00i+8ZZUAWwaUKrRP3gi2udCRKV?= =?us-ascii?Q?ySCcT7DybEXll7xscx2K0DqEQsIMboawKb0gPlg43QrQy36ZK/NX9vZjC4VU?= =?us-ascii?Q?9TxQmDeECA=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: d776e67f-90ff-4163-d5ca-08def6f25685 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB4827.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Aug 2026 15:16:22.8656 (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: WFyUV2A/Rba/mQhLB0Fa9wxq5gcc/TXfvrNy5J1FfI9L5Ukw2XAlS5qBCCp0hzhcpUEx3QQOU4qET3H5Mw34VQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8327 Proxy execution retains mutex-blocked donors on the runqueue so their scheduling context can execute a lock owner. sched_ext cannot safely retain such donors unless the BPF scheduler explicitly participates in their admission and ordering. Make sched_ext reject retained donors by default. Implement scx_allow_proxy_exec() to force blocked EXT tasks through the regular block path in schedule(). Also fully deactivate any retained proxy donor in sched_change_begin() before changing its scheduling class. This prevents sched_setscheduler(), PI transitions and sched_ext activation from carrying an existing proxy session into the new class. Some RT/DL PI transitions could usefully preserve the proxy session. For example, an RT waiter can boost a FAIR donor which is itself blocked on a non-PI mutex; retaining the donor would allow the boosted context to keep proxy-executing that mutex owner. Doing so safely requires defining which scheduling classes can carry retained proxy state across a transition. Keep the conservative reset for now and leave compatible RT/DL PI chains for future work. This is a preparatory change to support proxy execution with sched_ext. Signed-off-by: Andrea Righi --- kernel/sched/core.c | 9 +++++++++ kernel/sched/ext/ext.c | 2 +- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 08b4245a8f6b0..26d351ac27a80 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11235,6 +11235,15 @@ sched_change_begin(struct task_struct *p, const struct sched_class *next_class, flags |= DEQUEUE_NOCLOCK; } + /* + * Don't carry retained proxy state across scheduling class changes. + * Compatible RT/DL PI transitions could preserve the session so that a + * boosted donor continues proxy-executing its lock owner. Defining which + * class transitions can safely retain that state is left for future work. + */ + if ((flags & DEQUEUE_CLASS) && next_class != p->sched_class) + sched_proxy_block_task(rq, p); + if ((flags & DEQUEUE_CLASS) && p->sched_class->switching_from) p->sched_class->switching_from(rq, p); diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 4f2b0f1583989..5efbd80304dae 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -26,7 +26,7 @@ DEFINE_RAW_SPINLOCK(scx_sched_lock); bool scx_allow_proxy_exec(const struct task_struct *p) { - return true; + return p->sched_class != &ext_sched_class; } /* -- 2.55.0