From: Russell Miller <rmiller@duskglow.com>
A BUG or an oops will often leave a machine in a useless state. There is no
way to remotely recover the machine from that state.
The patch adds a /proc/sys/kernel/panic_on_oops sysctl which, when set, will
cause the x86 kernel to call panic() at the end of the oops handler. If the
user has also set /proc/sys/kernel/panic then a reboot will occur.
The implementation will try to sleep for a while before panicing so the oops
info has a chance of hitting the logs.
The implementation is designed so that other architectures can easily do this
in their oops handlers.
Documentation/sysctl/kernel.txt | 12 ++++++++++++
arch/i386/kernel/traps.c | 9 +++++++++
include/linux/kernel.h | 1 +
include/linux/sysctl.h | 1 +
kernel/panic.c | 7 +++----
kernel/sysctl.c | 2 ++
6 files changed, 28 insertions(+), 4 deletions(-)
diff -puN arch/i386/kernel/traps.c~panic-on-oops arch/i386/kernel/traps.c
--- 25/arch/i386/kernel/traps.c~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/arch/i386/kernel/traps.c 2003-04-02 21:57:44.000000000 -0800
@@ -302,6 +302,15 @@ void die(const char * str, struct pt_reg
show_registers(regs);
bust_spinlocks(0);
spin_unlock_irq(&die_lock);
+ if (in_interrupt())
+ panic("Fatal exception in interrupt");
+
+ if (panic_on_oops) {
+ printk(KERN_EMERG "Fatal exception: panic in 5 seconds\n");
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule_timeout(5 * HZ);
+ panic("Fatal exception");
+ }
do_exit(SIGSEGV);
}
diff -puN include/linux/kernel.h~panic-on-oops include/linux/kernel.h
--- 25/include/linux/kernel.h~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/include/linux/kernel.h 2003-04-02 21:50:15.000000000 -0800
@@ -104,6 +104,7 @@ static inline void console_verbose(void)
extern void bust_spinlocks(int yes);
extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */
+extern int panic_on_oops;
extern int tainted;
extern const char *print_tainted(void);
diff -puN include/linux/sysctl.h~panic-on-oops include/linux/sysctl.h
--- 25/include/linux/sysctl.h~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/include/linux/sysctl.h 2003-04-02 21:50:15.000000000 -0800
@@ -130,6 +130,7 @@ enum
KERN_CADPID=54, /* int: PID of the process to notify on CAD */
KERN_PIDMAX=55, /* int: PID # limit */
KERN_CORE_PATTERN=56, /* string: pattern for core-file names */
+ KERN_PANIC_ON_OOPS=57, /* int: whether we will panic on an oops */
};
diff -puN kernel/panic.c~panic-on-oops kernel/panic.c
--- 25/kernel/panic.c~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/kernel/panic.c 2003-04-02 21:50:15.000000000 -0800
@@ -20,6 +20,8 @@
asmlinkage void sys_sync(void); /* it's really int */
int panic_timeout;
+int panic_on_oops;
+int tainted;
struct notifier_block *panic_notifier_list;
@@ -28,7 +30,6 @@ static int __init panic_setup(char *str)
panic_timeout = simple_strtoul(str, NULL, 0);
return 1;
}
-
__setup("panic=", panic_setup);
/**
@@ -51,7 +52,7 @@ NORET_TYPE void panic(const char * fmt,
bust_spinlocks(1);
va_start(args, fmt);
- vsprintf(buf, fmt, args);
+ vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
printk(KERN_EMERG "Kernel panic: %s\n",buf);
if (in_interrupt())
@@ -123,5 +124,3 @@ const char *print_tainted()
snprintf(buf, sizeof(buf), "Not tainted");
return(buf);
}
-
-int tainted = 0;
diff -puN kernel/sysctl.c~panic-on-oops kernel/sysctl.c
--- 25/kernel/sysctl.c~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/kernel/sysctl.c 2003-04-02 21:50:15.000000000 -0800
@@ -275,6 +275,8 @@ static ctl_table kern_table[] = {
#endif
{KERN_PIDMAX, "pid_max", &pid_max, sizeof (int),
0600, NULL, &proc_dointvec},
+ {KERN_PANIC_ON_OOPS,"panic_on_oops",
+ &panic_on_oops,sizeof(int),0644,NULL,&proc_dointvec},
{0}
};
diff -puN Documentation/sysctl/kernel.txt~panic-on-oops Documentation/sysctl/kernel.txt
--- 25/Documentation/sysctl/kernel.txt~panic-on-oops 2003-04-02 21:50:15.000000000 -0800
+++ 25-akpm/Documentation/sysctl/kernel.txt 2003-04-02 21:50:15.000000000 -0800
@@ -204,6 +204,18 @@ software watchdog, the recommended setti
==============================================================
+panic_on_oops:
+
+Controls the kernel's behaviour when an oops or BUG is encountered.
+
+0: try to continue operation
+
+1: delay a few seconds (to give klogd time to record the oops output) and
+ then panic. If the `panic' sysctl is also non-zero then the machine will
+ be rebooted.
+
+==============================================================
+
pid_max:
PID allocation wrap value. When the kenrel's next PID value
_