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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?tlwR2NyjGfSilWa7h0srTelQ8sFz84PpFdAfd5dNMGzZaEpDXoKJ5ESyrS3n?= =?us-ascii?Q?/4voWIj5GuRvvAfEI9dKueIDJPhKh94Aiqw6Gl3MfjFVTyR9oci9oGIuSbmm?= =?us-ascii?Q?LzJUz1hJev89afZIbPpLNbisoY8oK5P1fpgwhEvpO2On7iAJZyCMCsEKio8J?= =?us-ascii?Q?WIKzY4xkPH6IVHWCNJvUrvIWGUpk0dASdXBNI3zC4Xa9H19Wzvk6pr5bKA9I?= =?us-ascii?Q?gJqpeJCZw6dUYfXnzL2yMgZkAdRi+ueOHBws5bpIyAS7JWU45XJulQgbDddc?= =?us-ascii?Q?ucAqdpnaQtjFDt1AXQ6CjNkk0kTFK/7MChqXjTMMLnP0gFPWI7nvG1ca3K3P?= =?us-ascii?Q?t0bzZUoBj+e43/R54b8LgvD4cu5bECIML2BWJw9qHXI0HluH/0XNlfUCOkRv?= =?us-ascii?Q?BqOPAA46DO+SDYDFrefp101rbiyEGSX0jFQhBnWjtK23y0BHHL2Ov1MfJTqo?= =?us-ascii?Q?0KnXv9acP9ZyT88+c8utbd82NrmCdcS6JtqJ4aJdczDZeDCbfi4cFYpPwHom?= =?us-ascii?Q?hHMeq5n2AvIkHomC2fcWYxxYtwvx63HxxSkY23ESkw0GjYM7jQ4LAszP+0bY?= =?us-ascii?Q?MhbrxGBDy7tX0QoB38fAF30301wSD98mnlJWTrIE7p7Dh4eCZD5JJwa28lN7?= =?us-ascii?Q?54PBu9uWwxMqRGq6FCunF98wDqI7ED81Kgt4KZci94iDB287XFgCUykowiBT?= =?us-ascii?Q?HPxd2MHaPa3pYmzUYhsPpiUx5VXrtJQN7VTzOjr5g5b1n8Q/WLoWC/eoCDy6?= =?us-ascii?Q?upmnp7B1lclkQJnQGjnEoUrP7dkV7bl7sQTqfHFFd1x/7MLSO2cpu2ViiRvD?= =?us-ascii?Q?nJB4Kcty0I++uSPEDxFbmYIOo62u2kSghwPyKY1IxekCZplKVZSsNSRt9XyE?= =?us-ascii?Q?H5m825FQAmI/IU2xC5cdTFfN2tf+8zvvLMmIsiarWZta2gTic2GZma0n8U1L?= =?us-ascii?Q?zM50rEAAM9dbW9ph40OwzZTnL+9rKANWCHxqc0wKxTuDIS1nWidECWWIf7m2?= =?us-ascii?Q?pUIWqOSP4PwiYpG65Tjif6/ScEInpUyrpileib/LnkDqsEsQtJTFKMzk8mAZ?= =?us-ascii?Q?wA+kPnOXtXC4GW6pW/ErFQ8gWq0fBe950jTfUNIYpDJekkEddJsQuJo4e177?= =?us-ascii?Q?Ogia3FJbCc9RNcUyVhH1c9u7TYWkjxRkjNjLbmAbvD0/3Wxml3nGMKvVCPUV?= =?us-ascii?Q?SPznuSywiDdBjPhcX28+pZbVTw8TxgwELAc6B4s66WSZTB85B5FJDW2X4zfz?= =?us-ascii?Q?dDDjG/bhu9TEk+fE0A6JhJD9d2hbZ1/bNqMbA/06r7GAD6gaPiZbiN3P9pwT?= =?us-ascii?Q?qLdc4IxHxRlGjibnCGB7cmypAuaVcS3Us4mrPp5NrDckohPzRwt1qUZBiwI9?= =?us-ascii?Q?yAb8fj51zKPzjL3alZzUrNwjapB1AjDgRUnYmn6HpXH338/56/vqWYEdm2iZ?= =?us-ascii?Q?BEGjq3niNBiYKJ2SNU1M2fi59uAvHXGKwShXwxuLffzq0/QwNeoaT6iyiOxo?= =?us-ascii?Q?qzbc56dLmNnu1JXC0gmv5nAnc2fknlqq0BBugAO2HmBC343sHMdRKfVa6T65?= =?us-ascii?Q?CtxZaLbjI+A3NeoQLfuKjHH/1YAwZodwOj++bJ4aYj0JPk+kGuZRiLKsfsRD?= =?us-ascii?Q?Ur8rOAiwk1xv1vABYjBDmvu2q/pHMA5dAwN7341d5G7W7TXXK67JbJoJ7/vR?= =?us-ascii?Q?HteZE/BnT1g0pWYHEferykLZcY/xWoE5Aj/IfJJRaGsbV44t5revXwo4HEVm?= =?us-ascii?Q?hsGQA+Fkyw=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 353d9e07-f0f0-47cb-5fee-08df07660a85 X-MS-Exchange-CrossTenant-AuthSource: CH2PR12MB4824.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Aug 2026 13:44:58.0068 (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: fEQqPt3xIZf4+zhGq/2ObxLcwh+5s8q1/UKbx4ZrFhSGIsLDYgD0SopcVvxTkxnBlkUZdxmFTSQ7FW6UBWaHzQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6755 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 f142ab455b797..4bd956182af8d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11302,6 +11302,15 @@ 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 f3e59f4fad4ac..d5ed996ebfb4c 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