Sorry, I don't understand. If it was not clear, let me repeat that I know nothing about kernel-rt. On 11/02, Sebastian Andrzej Siewior wrote: > On 2020-11-02 18:01:33 [+0100], Oleg Nesterov wrote: > > > So it seems I should send V2 which uses raw_spin_(un)lock_irq(). > > > > Or even _irqsave() like ptrace_freeze_traced() does? Although this looks > > confusing, exactly because ptrace_freeze_traced() calls task_is_traced() > > which does raw_spin_lock_irq(). > > Urgh. Judging from > release_task() > -> write_lock_irq(&tasklist_lock); > -> ptrace_release_task(); > -> ptrace_unlink(); > -> __ptrace_unlink(); > -> task_is_traced(). > > it will break on !RT so irqsave is indeed needed. Why? task_is_traced() does raw_spin_lock_irq() under ifdef(CONFIG_PREEMPT_RT). Oleg.
