Allow users to force a panic on NMI From: Don Zickus To quote Alan Cox: The default Linux behaviour on an NMI of either memory or unknown is to continue operation. For many environments such as scientific computing it is preferable that the box is taken out and the error dealt with than an uncorrected parity/ECC error get propogated. A small number of systems do generate NMI's for bizarre random reasons such as power management so the default is unchanged. In other respects the new proc/sys entry works like the existing panic controls already in that directory. This is separate to the edac support - EDAC allows supported chipsets to handle ECC errors well, this change allows unsupported cases to at least panic rather than cause problems further down the line. Signed-off-by: Don Zickus Signed-off-by: Andi Kleen --- This is just a refreshed post of Alan's original patch , with hopes this time it sticks. :) It applies cleanly on top of my other nmi patches. Cheers, Don --- arch/i386/kernel/traps.c | 6 ++++++ arch/x86_64/kernel/traps.c | 6 ++++++ include/linux/kernel.h | 1 + include/linux/sysctl.h | 1 + kernel/panic.c | 1 + kernel/sysctl.c | 8 ++++++++ 6 files changed, 23 insertions(+) Index: linux/arch/i386/kernel/traps.c =================================================================== --- linux.orig/arch/i386/kernel/traps.c +++ linux/arch/i386/kernel/traps.c @@ -602,6 +602,8 @@ static void mem_parity_error(unsigned ch "to continue\n"); printk(KERN_EMERG "You probably have a hardware problem with your RAM " "chips\n"); + if (panic_on_unrecovered_nmi) + panic("NMI: Not continuing"); /* Clear and disable the memory parity error line. */ clear_mem_error(reason); @@ -637,6 +639,10 @@ static void unknown_nmi_error(unsigned c reason, smp_processor_id()); printk("Dazed and confused, but trying to continue\n"); printk("Do you have a strange power saving mode enabled?\n"); + + if (panic_on_unrecovered_nmi) + panic("NMI: Not continuing"); + } static DEFINE_SPINLOCK(nmi_print_lock); Index: linux/arch/x86_64/kernel/traps.c =================================================================== --- linux.orig/arch/x86_64/kernel/traps.c +++ linux/arch/x86_64/kernel/traps.c @@ -618,6 +618,8 @@ mem_parity_error(unsigned char reason, s { printk("Uhhuh. NMI received. Dazed and confused, but trying to continue\n"); printk("You probably have a hardware problem with your RAM chips\n"); + if (panic_on_unrecovered_nmi) + panic("NMI: Not continuing"); /* Clear and disable the memory parity error line. */ reason = (reason & 0xf) | 4; @@ -643,6 +645,10 @@ unknown_nmi_error(unsigned char reason, { printk("Uhhuh. NMI received for unknown reason %02x.\n", reason); printk("Dazed and confused, but trying to continue\n"); printk("Do you have a strange power saving mode enabled?\n"); + + if (panic_on_unrecovered_nmi) + panic("NMI: Not continuing"); + } /* Runs on IST stack. This code must keep interrupts off all the time. Index: linux/include/linux/kernel.h =================================================================== --- linux.orig/include/linux/kernel.h +++ linux/include/linux/kernel.h @@ -179,6 +179,7 @@ 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_timeout; extern int panic_on_oops; +extern int panic_on_unrecovered_nmi; extern int tainted; extern const char *print_tainted(void); extern void add_taint(unsigned); Index: linux/kernel/sysctl.c =================================================================== --- linux.orig/kernel/sysctl.c +++ linux/kernel/sysctl.c @@ -645,6 +645,14 @@ static ctl_table kern_table[] = { #endif #if defined(CONFIG_X86) { + .ctl_name = KERN_PANIC_ON_NMI, + .procname = "panic_on_unrecovered_nmi", + .data = &panic_on_unrecovered_nmi, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, + { .ctl_name = KERN_BOOTLOADER_TYPE, .procname = "bootloader_type", .data = &bootloader_type, Index: linux/include/linux/sysctl.h =================================================================== --- linux.orig/include/linux/sysctl.h +++ linux/include/linux/sysctl.h @@ -150,6 +150,7 @@ enum KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */ KERN_COMPAT_LOG=73, /* int: print compat layer messages */ KERN_NMI_WATCHDOG=74, /* int: enable/disable nmi watchdog */ + KERN_PANIC_ON_NMI=75, /* int: whether we will panic on an unrecovered */ }; Index: linux/kernel/panic.c =================================================================== --- linux.orig/kernel/panic.c +++ linux/kernel/panic.c @@ -21,6 +21,7 @@ #include int panic_on_oops; +int panic_on_unrecovered_nmi; int tainted; static int pause_on_oops; static int pause_on_oops_flag;