Overview
作为一个 Linux 平台软件工程师，时常面对 panic 的世界。每当早晨打开电脑，看到 teams 人影闪动：”Jianguo，刚刚发现系统 crash 了，请有空看下现场吗？” 这时候我的内心充满了 panic， 真似 “衣带渐宽终不悔，为伊消得人憔悴”， 还似 “天不老，情难绝。心似双丝网，中有千千结” 啊！是时候再次了解下内核 panic 的流程了！
panic flow
smp_send_stop
smp_send_stop is very useful, it will send the IPI_CPU_STOP to other cores online and other cores will dump the stack trace.
panic_print
| bit0 | print all tasks info |
|---|---|
| bit1 | print system memory info |
| bit2 | print timer info |
| bit3 | print locks info if CONFIG_LOCKDEP is on |
| bit4 | print ftrace buffer |
| bit5 | print all printk messages in buffer |
| bit6 | print all CPUs backtrace (if available in the arch) |
So for example to print tasks and memory info on panic, user can:
echo 3 > /proc/sys/kernel/panic_print
References
Documentation for /proc/sys/kernel/ — The Linux Kernel documentation The kernel’s command-line parameters — The Linux Kernel documentation