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> > + /* > > + * Tasks pinned to a single CPU (per-CPU kthreads via > > + * kthread_bind(), tasks under migrate_disable()) cannot > > + * be moved to @owner_cpu. proxy_migrate_task() uses > > We only move it to donate the vruntime context. It is never actually > run there. > > > + * __set_task_cpu() which would silently violate the > > + * pinning and leave the task to run on a CPU outside > > + * its cpus_ptr once it is unblocked. Deactivate it on > > For the task to run as normal, p->is_blocked needs to be cleared. It is > only done in the wakeup path (and sometimes in find_proxy_task() if > the task is rq->curr) which ensures all the affinity / migrate disable > bits get fixed when the task gets to actually run. > > Where / how is this being violated? > > > + * this CPU; the owner running elsewhere will wake @p > > + * back up when the mutex becomes available. > > + */ > > + if (p->nr_cpus_allowed == 1 || is_migration_disabled(p)) { > > + __clear_task_blocked_on(p, NULL); > > + goto deactivate; > > + } > > Proxy depends on the ability to migrate the donor context to owner's > CPU without actually running the task. The task is superficially on > the CPU only to give it's runtime share to the lock owner. Feels like > you are tripping a shortcoming in ext core if this is a problem. Agree with all of the above. As I mention in the other email, I had this in the previous version, because I was hitting migration-disabled errors. Maybe they were related to an issue in the sched_ext core, I'll remove this and repeat my tests. Thanks, -Andrea