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Subject[tip:x86/urgent] x86: Add sysctl to allow panic on IOCK NMI error
Commit-ID:  0b2f282236572b333d5d74264b04f214c24aba18
Gitweb: http://git.kernel.org/tip/0b2f282236572b333d5d74264b04f214c24aba18
Author: Kurt Garloff <garloff@suse.de>
AuthorDate: Wed, 24 Jun 2009 14:32:11 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 25 Jun 2009 22:02:58 +0200

x86: Add sysctl to allow panic on IOCK NMI error

This patch introduces a new 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
bank's databases.

[ SuSE has been shipping it for a while, it was done at the
request of a large database vendor, for their users. ]

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>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
LKML-Reference: <20090624213211.GA11291@kroah.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
arch/x86/kernel/dumpstack.c | 1 +
arch/x86/kernel/traps.c | 3 +++
include/linux/kernel.h | 1 +
kernel/sysctl.c | 8 ++++++++
kernel/sysctl_check.c | 1 +
5 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 95ea5fa..c840571 100644
--- 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;
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index a0f48f5..5204332 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -346,6 +346,9 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
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);
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index fac104e..d6320a3 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -303,6 +303,7 @@ extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in
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);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 62e4ff9..fba42ed 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -744,6 +744,14 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
{
+ .ctl_name = CTL_UNNUMBERED,
+ .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,
diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index b38423c..e1d8e0f 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -104,6 +104,7 @@ static const struct trans_ctl_table trans_kern_table[] = {
{ 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" },
{}
};


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