(2011/02/10 1:35), Seiji Aguchi wrote: > Hi, > > I submitted a quite similar patch last December. > > http://www.spinics.net/lists/linux-mm/msg13157.html > > I retry it with different description of the purpose. > > [Changelog] > from v1: > - Change name of sysctl parameter ,kexec_on_mce, to kexec_on_hwerr. > - Move variable declaration from <asm/mce.h> to <kernel/panic.h>. > - Remove CONFIG_X86_MCE in *.c files. > - Modify [Purpose]/[Patch Description]. > > [Purpose] > There are some logging features of firmware/hardware, SEL,BMC, etc, in enterprise servers. > We investigate the firmware/hardware logs first when MCE occurred and replace the broken hardware. > So, memory dump is not necessary for detecting root cause of machine check. > Also, we can reduce down-time by skipping kdump. > > Of course, there are a lot of servers which don't have logging features of firmware/hardware. > So, I proposed a option controlling kexec behaviour when hardware error occurred. > > [Patch Description] > This patch adds a sysctl option ,kernel.kexec_on_hwerr, controlling kexec behaviour when hardware error occurred. > > - Permission > - 0644 > - Value(default is "1") > - non-zero: Kexec is enabled regardless of hardware error. > - 0: Kexec is disabled when MCE occurred. > > > Matrix of kernel.kexec_on_hwerr value ,hardware error and kexec > > -------------------------------------------------- > kernel.kexec_on_hwerr| hardware error | kexec > -------------------------------------------------- > non-zero | occurred | enabled > ----------------------------- > | not occurred | enabled > -------------------------------------------------- > 0 | occurred | disabled > |---------------------------- > | not occurred | enabled > -------------------------------------------------- > > > Any comments and suggestions are welcome. > > Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx> > > --- > Documentation/sysctl/kernel.txt | 11 +++++++++++ > arch/x86/kernel/cpu/mcheck/mce.c | 2 ++ > include/linux/kernel.h | 2 ++ > include/linux/sysctl.h | 1 + > kernel/panic.c | 15 ++++++++++++++- > kernel/sysctl.c | 8 ++++++++ > kernel/sysctl_binary.c | 1 + > mm/memory-failure.c | 2 ++ > 8 files changed, 41 insertions(+), 1 deletions(-) > > diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 11d5ced..3159111 100644 > --- a/Documentation/sysctl/kernel.txt > +++ b/Documentation/sysctl/kernel.txt > @@ -34,6 +34,7 @@ show up in /proc/sys/kernel: > - hotplug > - java-appletviewer [ binfmt_java, obsolete ] > - java-interpreter [ binfmt_java, obsolete ] > +- kexec_on_hwerr [ x86 only ] > - kptr_restrict > - kstack_depth_to_print [ X86 only ] > - l2cr [ PPC only ] > @@ -261,6 +262,16 @@ This flag controls the L2 cache of G3 processor boards. If 0, the cache is disabled. Enabled if nonzero. > > ============================================================== > +kexec_on_hwerr: (X86 only) > + > +Controls the behaviour of kexec when panic occurred due to hardware > +error. > +Default value is 1. > + > +0: Kexec is disabled. > +non-zero: Kexec is enabled. > + > +============================================================== > > kptr_restrict: > > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > index d916183..e76b47b 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -944,6 +944,8 @@ void do_machine_check(struct pt_regs *regs, long error_code) > > percpu_inc(mce_exception_count); > > + hwerr_flag = 1; > + > if (notify_die(DIE_NMI, "machine check", regs, error_code, > 18, SIGKILL) == NOTIFY_STOP) > goto out; Now x86 supports some recoverable machine check, so setting flag here will prevent running kexec on systems that have encountered such recoverable machine check and recovered. I think mce_panic() is proper place to set this flag "hwerr_flag". > diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2fe6e84..c2fba7c 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -242,6 +242,8 @@ extern void add_taint(unsigned flag); extern int test_taint(unsigned flag); extern unsigned long get_taint(void); extern int root_mountflags; > +extern int kexec_on_hwerr; > +extern int hwerr_flag; > > extern bool early_boot_irqs_disabled; > > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 7bb5cb6..8ae5bfe 100644 > --- a/include/linux/sysctl.h > +++ b/include/linux/sysctl.h > @@ -153,6 +153,7 @@ enum > KERN_MAX_LOCK_DEPTH=74, /* int: rtmutex's maximum lock depth */ > KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */ > KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */ > + KERN_KEXEC_ON_HWERR=77, /* int: bevaviour of kexec for hardware error > +*/ > }; > > > diff --git a/kernel/panic.c b/kernel/panic.c index 991bb87..84c1d2e 100644 > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -28,6 +28,8 @@ > #define PANIC_BLINK_SPD 18 > > int panic_on_oops; > +int kexec_on_hwerr = 1; > +int hwerr_flag; > static unsigned long tainted_mask; > static int pause_on_oops; > static int pause_on_oops_flag; > @@ -45,6 +47,16 @@ static long no_blink(int state) > return 0; > } > > +static int kexec_should_skip(void) > +{ > + if (!kexec_on_hwerr && hwerr_flag) { > + printk(KERN_WARNING "Kexec is skipped because hardware error " > + "occurred.\n"); > + return 1; > + } > + return 0; > +} > + > /* Returns how long it waited in ms */ > long (*panic_blink)(int state); > EXPORT_SYMBOL(panic_blink); > @@ -86,7 +98,8 @@ NORET_TYPE void panic(const char * fmt, ...) > * everything else. > * Do we want to call this before we try to display a message? > */ > - crash_kexec(NULL); > + if (!kexec_should_skip()) > + crash_kexec(NULL); > > kmsg_dump(KMSG_DUMP_PANIC); > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 0f1bd83..f78edd8 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -811,6 +811,14 @@ static struct ctl_table kern_table[] = { > .mode = 0644, > .proc_handler = proc_dointvec, > }, > + { > + .procname = "kexec_on_hwerr", > + .data = &kexec_on_hwerr, > + .maxlen = sizeof(int), > + .mode = 0644, > + .proc_handler = proc_dointvec, > + }, > + > #endif > #if defined(CONFIG_MMU) > { > diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c index b875bed..8d572ca 100644 > --- a/kernel/sysctl_binary.c > +++ b/kernel/sysctl_binary.c > @@ -137,6 +137,7 @@ static const struct bin_table bin_kern_table[] = { > { CTL_INT, KERN_COMPAT_LOG, "compat-log" }, > { CTL_INT, KERN_MAX_LOCK_DEPTH, "max_lock_depth" }, > { CTL_INT, KERN_PANIC_ON_NMI, "panic_on_unrecovered_nmi" }, > + { CTL_INT, KERN_KEXEC_ON_HWERR, "kexec_on_hwerr" }, > {} > }; > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 0207c2f..0178f47 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -994,6 +994,8 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) > int res; > unsigned int nr_pages; > > + hwerr_flag = 1; > + > if (!sysctl_memory_failure_recovery) > panic("Memory failure from trap %d on page %lx", trapno, pfn); > For similar reason, setting flag here is not good for systems working after isolating some poisoned memory page. Why not: if (!sysctl_memory_failure_recovery) { hwerr_flag = 1; panic("Memory failure from trap %d on page %lx", trapno, pfn); } Thanks, H.Seto -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>