From 9ab181fa9ff73a38fccd0a4f1c40a38dfe62b535 Mon Sep 17 00:00:00 2001
From: Don Zickus <dzickus@redhat.com>
Date: Tue, 4 Jan 2011 22:38:07 -0500
Subject: [PATCH] x86: Only call smp_processor_id in non-preempt cases
There are some paths that walk the die_chain with preemption on.
Make sure we are in an NMI call before we start doing anything.
This was triggered by do_general_protection calling notify_die
with DIE_GPF.
Reported-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Don Zickus <dzickus@redhat.com>
LKML-Reference: <1294198689-15447-1-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/apic/hw_nmi.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index c57d0b599448..2b40a6045da2 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -51,7 +51,7 @@ arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
{
struct die_args *args = __args;
struct pt_regs *regs;
- int cpu = smp_processor_id();
+ int cpu;
switch (cmd) {
case DIE_NMI:
@@ -63,6 +63,7 @@ arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
}
regs = args->regs;
+ cpu = smp_processor_id();
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
--
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