Re: [Crash-utility] [PATCH] Fix x86 initialization for {hard, soft}irq_ctx

Dave Anderson <anderson(a)redhat.com&gt; writes: >> >> crash> bt >> >> PID: 0 TASK: c1da8b00 CPU: 0 COMMAND: "swapper/0" >> >> #0 [c1da1f60] __schedule at c19fe305 >> >> #1 [c1da1fa0] schedule at c19febb3 >> >> #2 [c1da1fac] schedule_preempt_disabled at c19ff0a2 >> >> #3 [c1da1fb4] cpu_startup_entry at c10a9580 >> >> crash> bt 45 >> >> PID: 45 TASK: f57d3a00 CPU: 3 COMMAND: "kworker/3:1" >> >> bt: cannot resolve stack trace: >> >> bt: Task in user space -- no backtrace >> >> >> >> In above case, looks like failed to detect panic cpu, and "bt 45" also >> >> not working. >> >> crash> bt 45 >> PID: 45 TASK: f57d3a00 CPU: 3 COMMAND: "kworker/3:1" >> bt: cannot resolve stack trace: >> bt: Task in user space -- no backtrace Debugged this case. The root cause is nested stack of softirq => hardirq. Now doesn't handle it correctly, and the patch attacked. BTW, with this patch, "bt -t" seems to be working at least. "bt" is failed sometime by confusion of stack-frame detection, this one is harder to fix.

[BTW, current x86_get_pc() uses inactive_task_frame_ret_addr to get pc. However, inactive_task_frame is only valid if task is sleeping state. (running task may overwrite inactive_task_frame already.) I'm not sure whether we should check is_task_active() or not. Even if checking is_task_active(), we can't get pc correctly anyway.]

Thanks. -- OGAWA Hirofumi <hirofumi(a)mail.parknet.co.jp&gt; [Text Documents:p1-fix-x86-nest-stack.patch]