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

----- Original Message ----- > 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. OK thanks, I'll give this patch a test run.

> > [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.] Well, x86_get_pc() should only be called in the case of sleeping tasks because each dumpfile type has its own function to try to find the active task registers. For example, on a kdump: cmd_bt() back_trace() get_kdump_regs() get_netdump_regs() get_netdump_regs_x86() get_netdump_regs_x86() *should* find the starting point hooks. If it fails to do so, it will default to machdep->get_stack_frame() and ultimately x86_get_pc(). So if it gets there, the backtrace is pretty much guaranteed to be invalid. Thanks, Dave > Thanks. > -- > OGAWA Hirofumi <hirofumi(a)mail.parknet.co.jp&gt; > > > > [Text Documents:p1-fix-x86-nest-stack.patch] > -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility