Schedule tasks where we've seen but not processed PTRACE_EVENT_EXIT #3883
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If we see the PTRACE_EVENT_EXIT for a task while running a different task in unlimited-ticks mode in `Scheduler::reschedule`, it looks like nothing ever actually calls `handle_ptrace_exit_event` on it, and so nothing ever PTRACE_CONT's the task out of the exit-stop and into the zombie state. This seems to manifest itself as rr not reaping processes properly when they receive asynchronous core-dumping signals (e.g. SIGSEGV sent by `raise` or `kill`). Fix this issue by checking if there's a pending PTRACE_EVENT_EXIT to deal with on the task in `Scheduler::is_task_runnable`, and allowing the task to be executed if so. Fixes rr-debugger#3882
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If we see the PTRACE_EVENT_EXIT for a task while running a different task in unlimited-ticks mode in
Scheduler::reschedule, it looks like nothing ever actually callshandle_ptrace_exit_eventon it, and so nothing ever PTRACE_CONT's the task out of the exit-stop and into the zombie state.This seems to manifest itself as rr not reaping processes properly when they receive asynchronous core-dumping signals (e.g. SIGSEGV sent by
raiseorkill).Fix this issue by checking if there's a pending PTRACE_EVENT_EXIT to deal with on the task in
Scheduler::is_task_runnable, and allowing the task to be executed if so.Fixes #3882