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

Eric W. Biederman
2009-06-25T18:16:05Z

Greg KH <gregkh@suse.de> writes:

> 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.

Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>

New binary sysctls are not allowed. Please remove the
sysctl.h and .ctl_name portions.

see:
Documentation/sysctl/ctl_unnumbered.txt
Documentation/feature-remove-schedule.txt

I have a set of patches that should make this kind of thing
fail to compile for .32. Hopefully I can get that out in
the next couple of days. Making problems like this easier
to spot and deal with.

> 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" },
> {}
> };
>
>
> --
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