[PATCH] x86: sysctl to allow panic on IOCK NMI error

Greg KH
2009-06-24T21:36:27Z

From: Kurt Garloff <garloff@suse.de>

This patch introduces a sysctl /proc/sys/kernel/panic_on_io_nmi, which
defaults to 0 (off).

When enabled, the kernel panics when the kernel receives an NMI caused
by an IO error.

The IO error triggered NMI indicates a serious system condition, which
could result in IO data corruption. Rather than contiuing, panicing and
dumping might be a better choice, so one can figure out what's causing
the IO error.

This could be especially important to companies running IO intensive
applications where corruption must be avoided, e.g. a banks databases.

Signed-off-by: Kurt Garloff <garloff@suse.de>
Signed-off-by: Roberto Angelino <robertangelino@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---

I don't know why this wasn't sent to you before now, sorry about that.
SuSE has been shipping it for a while, it was done at the request of a
large database vendor, for their users. Can you queue it up for .32?
- gregkh

arch/x86/kernel/dumpstack.c | 1 +
arch/x86/kernel/traps.c | 3 +++
include/linux/kernel.h | 1 +
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 8 ++++++++
kernel/sysctl_check.c | 1 +
6 files changed, 15 insertions(+)

--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -22,6 +22,7 @@
#include "dumpstack.h"

int panic_on_unrecovered_nmi;
+int panic_on_io_nmi;
unsigned int code_bytes = 64;
int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
static int die_counter;
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -346,6 +346,9 @@ io_check_error(unsigned char reason, str
printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
show_registers(regs);

+ if (panic_on_io_nmi)
+ panic("NMI IOCK error: Not continuing");
+
/* Re-enable the IOCK line, wait for a few seconds */
reason = (reason & 0xf) | 8;
outb(reason, 0x61);
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -303,6 +303,7 @@ extern int oops_in_progress; /* If set,
extern int panic_timeout;
extern int panic_on_oops;
extern int panic_on_unrecovered_nmi;
+extern int panic_on_io_nmi;
extern const char *print_tainted(void);
extern void add_taint(unsigned flag);
extern int test_taint(unsigned flag);
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -163,6 +163,7 @@ enum
KERN_MAX_LOCK_DEPTH=74,
KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
+ KERN_PANIC_ON_IO_NMI=77, /* int: whether we will panic on an io NMI */
};

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -744,6 +744,14 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = KERN_PANIC_ON_IO_NMI,
+ .procname = "panic_on_io_nmi",
+ .data = &panic_on_io_nmi,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
.ctl_name = KERN_BOOTLOADER_TYPE,
.procname = "bootloader_type",
.data = &bootloader_type,
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -104,6 +104,7 @@ static const struct trans_ctl_table tran
{ KERN_MAX_LOCK_DEPTH, "max_lock_depth" },
{ KERN_NMI_WATCHDOG, "nmi_watchdog" },
{ KERN_PANIC_ON_NMI, "panic_on_unrecovered_nmi" },
+ { KERN_PANIC_ON_IO_NMI, "panic_on_io_nmi" },
{}
};