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From: Jin Dongming on 26 May 2010 22:50
This patch fixes do_machine_check() failure caused by DIE_NMI.

I do MCE tests on my machine. When I inject Uncorrected Error(UE) into
kernel, the messages of test failure are always gotten. This problem
is caused by the notification of DIE_NMI in the front of do_machine_check().
Because there are some notifications used DIE_NMI, and when they finish their
own work and return NOTIFY_STOP as a result. The result makes
do_machine_check() return at that time.

So we decide to delete the notification of DIE_NMI. It is because when UE error
happens, if one of the cpu is down caused by the error of hook function of
DIE_NMI, the error type of UE may be different with the real one. For example,

CPU0 CPU1
UE do_machine_check() do_machine_check()
| |
cpu down(hook error of DIE_NMI) cpu OK(no hook error of DIE_NMI)
|
wait CPU0 timeout
|
Fatal Error
(Timeout synchronizing machine
check over CPUs)

And I test this patch on x86_64. It works well.

Signed-off-by: Jin Dongming <jin.dongming(a)np.css.fujitsu.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi(a)jp.fujitsu.com>
---
arch/x86/kernel/cpu/mcheck/mce.c | 3 ---
1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 18cc425..5ed9df3 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -955,9 +955,6 @@ void do_machine_check(struct pt_regs *regs, long error_code)

percpu_inc(mce_exception_count);

- if (notify_die(DIE_NMI, "machine check", regs, error_code,
- 18, SIGKILL) == NOTIFY_STOP)
- goto out;
if (!banks)
goto out;

--
1.7.0.3

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Prev: [PATCH 7/8] ACPI: acpi_idle: touch TS_POLLING only in the non-MWAIT case
Next: [PATCH 8/8] intel_idle: create a native cpuidle driver for select intel processors