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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: XUsYPUumalcnYyTNBKuRU+Y+bAbx6KSBeOCeLOUKkUYx468T0TwznYMizkuys6VIOtIza3HhqwA6OO6RlgaKdEf+7eUyC6qUncoEnb7KTv9sLdUUGcYfzpJ2Ihvvnh3TY1m/IH0xaSGI3sGwtgofuXCnrirHW1Ezma5pgHA28fMnz1RlerRcG/OycyQIZA69o5rE05qEVVycDnGk1EQ2eUZlL3b6VXy6E0C4O6lwuaNyK1eeWI4FRy2m08f3kVBEvWAQFUhdbxysYOP2b257wZS8yrtbDfEqqbEDfTRwjqkziVDPB8co1QICv50q4xtHtuQnfJp8MpEVsJtWTSyVcYwP/KvRgQmIwrH2dzW9/lHEsuSSL6S63eZu1gzczsck7sHLZWUTFZlrhNWJnW12G004RfkqkXiap+9eZ9az6NaCsO5eqi4m+0+uoryLgzRj X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 May 2026 13:19:10.5495 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 82d9959c-9a79-43cc-1f62-08dea9dfba9d X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF000001F6.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6548 Hello Vasily, On 5/4/2026 6:01 PM, Vasily Gorbik wrote: > try_steal_cookie() avoids stealing src->core_pick and src->curr before > moving a task with the same cookie via move_queued_task_locked(). > > With proxy-exec, src->donor is the current scheduling context and may > differ from src->curr. Stealing it migrates a task that the source rq > still treats as current. For CFS, src cfs_rq->curr is left pointing > at the stolen entity and the next pick on src hits the WARN_ON_ONCE > in put_prev_entity(). > > Commit 7de9d4f94638 ("sched: Start blocked_on chain processing in > find_proxy_task()") tweaked the fair class logic so that the donor task > isn't migrated away while running the proxy. Do it similarly for > try_steal_cookie() and skip src->donor as well. > > Fixes: 7de9d4f94638 ("sched: Start blocked_on chain processing in find_proxy_task()") > Signed-off-by: Vasily Gorbik > --- > kernel/sched/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index b8871449d3c6..3cf5fb70814c 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6358,7 +6358,7 @@ static bool try_steal_cookie(int this, int that) > return false; > > do { > - if (p == src->core_pick || p == src->curr) > + if (p == src->core_pick || p == src->curr || p == src->donor) Although this solves the issue of stealing the donor, I'm a bit skeptical if proxy exec even works with core scheduling at all since __schedule() can override the decision of core_pick and the CPU may end up running a task with different core-cookie if it found the core_pick to be blocked on a mutex :-( > goto next; > > if (!is_cpu_allowed(p, this)) -- Thanks and Regards, Prateek