[PATCH] x86: all cpu backtrace
When a spinlock lockup occurs, arrange for the NMI code to emit an all-cpu
backtrace, so we get to see which CPU is holding the lock, and where.
Cc: Andi Kleen <ak@muc.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index eaafe23..171194c 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -22,6 +22,7 @@
#include <linux/percpu.h>
#include <linux/dmi.h>
#include <linux/kprobes.h>
+#include <linux/cpumask.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -42,6 +43,8 @@
static DEFINE_PER_CPU(unsigned long, perfctr_nmi_owner);
static DEFINE_PER_CPU(unsigned long, evntsel_nmi_owner[3]);
+static cpumask_t backtrace_mask = CPU_MASK_NONE;
+
/* this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's
* offset from MSR_P4_BSU_ESCR0. It will be the max for all platforms (for now)
*/
@@ -907,6 +910,16 @@
touched = 1;
}
+ if (cpu_isset(cpu, backtrace_mask)) {
+ static DEFINE_SPINLOCK(lock); /* Serialise the printks */
+
+ spin_lock(&lock);
+ printk("NMI backtrace for cpu %d\n", cpu);
+ dump_stack();
+ spin_unlock(&lock);
+ cpu_clear(cpu, backtrace_mask);
+ }
+
sum = per_cpu(irq_stat, cpu).apic_timer_irqs;
/* if the apic timer isn't firing, this cpu isn't doing much */
@@ -1033,6 +1046,19 @@
#endif
+void __trigger_all_cpu_backtrace(void)
+{
+ int i;
+
+ backtrace_mask = cpu_online_map;
+ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpus_empty(backtrace_mask))
+ break;
+ mdelay(1);
+ }
+}
+
EXPORT_SYMBOL(nmi_active);
EXPORT_SYMBOL(nmi_watchdog);
EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi);
diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index 7af9cb3..27e95e7 100644
--- a/arch/x86_64/kernel/nmi.c
+++ b/arch/x86_64/kernel/nmi.c
@@ -12,14 +12,15 @@
* Mikael Pettersson : PM converted to driver model. Disable/enable API.
*/
+#include <linux/nmi.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/sysdev.h>
-#include <linux/nmi.h>
#include <linux/sysctl.h>
#include <linux/kprobes.h>
+#include <linux/cpumask.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -41,6 +42,8 @@
static DEFINE_PER_CPU(unsigned, perfctr_nmi_owner);
static DEFINE_PER_CPU(unsigned, evntsel_nmi_owner[2]);
+static cpumask_t backtrace_mask = CPU_MASK_NONE;
+
/* this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's
* offset from MSR_P4_BSU_ESCR0. It will be the max for all platforms (for now)
*/
@@ -782,6 +785,7 @@
{
int sum;
int touched = 0;
+ int cpu = smp_processor_id();
struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
u64 dummy;
int rc=0;
@@ -799,6 +803,16 @@
touched = 1;
}
+ if (cpu_isset(cpu, backtrace_mask)) {
+ static DEFINE_SPINLOCK(lock); /* Serialise the printks */
+
+ spin_lock(&lock);
+ printk("NMI backtrace for cpu %d\n", cpu);
+ dump_stack();
+ spin_unlock(&lock);
+ cpu_clear(cpu, backtrace_mask);
+ }
+
#ifdef CONFIG_X86_MCE
/* Could check oops_in_progress here too, but it's safer
not too */
@@ -931,6 +945,19 @@
#endif
+void __trigger_all_cpu_backtrace(void)
+{
+ int i;
+
+ backtrace_mask = cpu_online_map;
+ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpus_empty(backtrace_mask))
+ break;
+ mdelay(1);
+ }
+}
+
EXPORT_SYMBOL(nmi_active);
EXPORT_SYMBOL(nmi_watchdog);
EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi);
diff --git a/include/asm-i386/nmi.h b/include/asm-i386/nmi.h
index 269d315..b04333e 100644
--- a/include/asm-i386/nmi.h
+++ b/include/asm-i386/nmi.h
@@ -5,6 +5,9 @@
#define ASM_NMI_H
#include <linux/pm.h>
+#include <asm/irq.h>
+
+#ifdef ARCH_HAS_NMI_WATCHDOG
/**
* do_nmi_callback
@@ -42,4 +45,9 @@
void __user *, size_t *, loff_t *);
extern int unknown_nmi_panic;
+void __trigger_all_cpu_backtrace(void);
+#define trigger_all_cpu_backtrace() __trigger_all_cpu_backtrace()
+
+#endif
+
#endif /* ASM_NMI_H */
diff --git a/include/asm-x86_64/nmi.h b/include/asm-x86_64/nmi.h
index f367d40..72375e7 100644
--- a/include/asm-x86_64/nmi.h
+++ b/include/asm-x86_64/nmi.h
@@ -77,4 +77,7 @@
extern int unknown_nmi_panic;
+void __trigger_all_cpu_backtrace(void);
+#define trigger_all_cpu_backtrace() __trigger_all_cpu_backtrace()
+
#endif /* ASM_NMI_H */
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index e16904e..acb4ed1 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -15,9 +15,14 @@
* disables interrupts for a long time. This call is stateless.
*/
#ifdef ARCH_HAS_NMI_WATCHDOG
+#include <asm/nmi.h>
extern void touch_nmi_watchdog(void);
#else
# define touch_nmi_watchdog() touch_softlockup_watchdog()
#endif
+#ifndef trigger_all_cpu_backtrace
+#define trigger_all_cpu_backtrace() do { } while (0)
+#endif
+
#endif
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index b6c4f89..479fd46 100644
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -7,6 +7,7 @@
*/
#include <linux/spinlock.h>
+#include <linux/nmi.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>
#include <linux/delay.h>
@@ -117,6 +118,9 @@
raw_smp_processor_id(), current->comm,
current->pid, lock);
dump_stack();
+#ifdef CONFIG_SMP
+ trigger_all_cpu_backtrace();
+#endif
}
}
}