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Commitabfc01077d("sched: Fix do_set_cpus_allowed() locking") overlooked that __balance_push_cpu_stop() calls select_fallback_rq() with rq->lock held. This makes that set_cpus_allowed_force() will recursively take rq->lock and the machine locks up. Run select_fallback_rq() earlier, without holding rq->lock. This opens up a race window where a task could get migrated out from under us, but that is harmless, we want the task migrated. select_fallback_rq() itself will not be subject to concurrency as it will be fully serialized by p->pi_lock, so there is no chance of set_cpus_allowed_force() getting called with different arguments and selecting different fallback CPUs for one task. Fixes:abfc01077d("sched: Fix do_set_cpus_allowed() locking") Reported-by: Jan Polensky <japo@linux.ibm.com> Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Jan Polensky <japo@linux.ibm.com> Closes: https://lore.kernel.org/oe-lkp/202510271206.24495a68-lkp@intel.com Link: https://patch.msgid.link/20251027110133.GI3245006@noisy.programming.kicks-ass.net