解决kernel panic - not syncing

kernel panic 出错会在屏幕上显示，看了下message文件、并没有相关记录。

kernel panic 主要有以下几个出错提示：

kernel panic - not syncing: Attempted to kill the idle task!
kernel panic - not syncing: killing interrupt handler!
Kernel Panic - not syncing：Attempted to kill init !

查看了一下 linux的源码文件，找到相关位置

kernel/panic.c

NORET_TYPE void panic(const char * fmt, ...)
{
static char buf[1024];
va_list args;

bust_spinlocks(1);
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
bust_spinlocks(0);


kernel/exit.c

if (unlikely(in_interrupt()))
panic("Aiee, killing interrupt handler!"); #中断处理
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!"); #空任务
if (unlikely(tsk->pid == 1))
panic("Attempted to kill init!"); #初始化



从其他源文件和相关文档看到应该有几种原因：

1、硬件问题

使用了 SCSI-device 并且使用了未知命令

#WDIOS_TEMPPANIC Kernel panic on temperature trip
# 
# The SETOPTIONS call can be used to enable and disable the card
# and to ask the driver to call panic if the system overheats.
# 
# If one uses a SCSI-device of unsupported type/commands, one
# immediately runs into a kernel-panic caused by Command Error. To better
# understand which SCSI-command caused the problem, I extended this
# specific panic-message slightly.
# 
#read/write causes a command error from
# the subsystem and this causes kernel-panic


2、系统过热
如果系统过热会调用panci，系统挂起

#WDIOS_TEMPPANIC Kernel panic on temperature trip
# 
# The SETOPTIONS call can be used to enable and disable the card
# and to ask the driver to call panic if the system overheats.


3、文件系统引起

#A variety of panics and hangs with /tmp on a reiserfs filesystem
#Any other panic, hang, or strange behavior
#
# It turns out that there's a limit of six environment variables on the
# kernel command line. When that limit is reached or exceeded, argument
# processing stops, which means that the 'root=' argument that UML
# usually adds is not seen. So, the filesystem has no idea what the
# root device is, so it panics.
# The fix is to put less stuff on the command line. Glomming all your
# setup variables into one is probably the best way to go.

Linux内核命令行有6个环境变量。如果即将达到或者已经超过了的话 root= 参数会没有传进去
启动时会引发panics错误。

vi grub.conf
#####################
title Red Hat Enterprise Linux AS (2.6.9-67.0.15.ELsmp)
root (hd0,0)
kernel /boot/vmlinuz-2.6.9-67.0.15.ELsmp ro root=LABEL=/
initrd /boot/initrd-2.6.9-67.0.15.ELsmp.img
title Red Hat Enterprise Linux AS-up (2.6.9-67.EL)
root (hd0,0)
kernel /boot/vmlinuz-2.6.9-67.EL ro root=LABEL=/
initrd /boot/initrd-2.6.9-67.EL.img

应该是 其中的 root=LABEL=/ 没有起作用。


4、内核更新
网上相关文档多半是因为升级内核引起的，建议使用官方标准版、稳定版

另外还有使用磁盘的lvm 逻辑卷，添加CPU和内存。可在BIOS中禁掉声卡驱动等不必要的设备。

也有报是ext3文件系统的问题。
解决： 手工编译内核，把 ext3相关的模块都编译进去，


5、处理panic后的系统自动重启

panic.c源文件有个方法，当panic挂起后，指定超时时间，可以重新启动机器

if (panic_timeout > 0)
{
int i;
/*
* Delay timeout seconds before rebooting the machine.
* We can't use the "normal" timers since we just panicked..
*/
printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
for (i = 0; i < panic_timeout; i++) {
touch_nmi_watchdog();
mdelay(1000);
}

修改方法：
/etc/sysctl.conf文件中加入
kernel.panic = 30 #panic错误中自动重启，等待时间为30秒
kernel.sysrq=1 #激活Magic SysRq！ 否则，键盘鼠标没有响应