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    Subject[PATCH] x86: fix duplicate calls of the nmi handler
    On 10.09.10 10:46:34, Ingo Molnar wrote:
    > > > I'll look at getting a trace of the thing, but if any of you has a
    > > > bright idea...

    I found another patch in my queue, which fixes a duplicate call of the
    nmi handler. Since I could not yet reproduce the bug, I am not sure if
    this fixes the problem, but it is worth a try.

    -Robert

    --

    From 037678d4231778c55ed1a19b53d24c7056ae8bbd Mon Sep 17 00:00:00 2001
    From: Robert Richter <robert.richter@amd.com>
    Date: Fri, 6 Aug 2010 20:45:51 +0200
    Subject: [PATCH] x86: fix duplicate calls of the nmi handler

    The commit:

    e40b172 x86: Move notify_die from nmi.c to traps.c

    moved the nmi handler call to default_do_nmi(). DIE_NMI_IPI and
    DIE_NMI are called subsequently now. If the return code is
    !NOTIFY_STOP, then the handlers are called twice. This patch fixes
    this.

    Signed-off-by: Robert Richter <robert.richter@amd.com>
    ---
    arch/x86/kernel/apic/hw_nmi.c | 1 -
    arch/x86/kernel/cpu/perf_event.c | 1 -
    arch/x86/oprofile/nmi_int.c | 1 -
    3 files changed, 0 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
    index cefd694..61a3ad7 100644
    --- a/arch/x86/kernel/apic/hw_nmi.c
    +++ b/arch/x86/kernel/apic/hw_nmi.c
    @@ -52,7 +52,6 @@ arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
    int cpu = smp_processor_id();

    switch (cmd) {
    - case DIE_NMI:
    case DIE_NMI_IPI:
    break;

    diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
    index 3efdf28..87dc9e2 100644
    --- a/arch/x86/kernel/cpu/perf_event.c
    +++ b/arch/x86/kernel/cpu/perf_event.c
    @@ -1219,7 +1219,6 @@ perf_event_nmi_handler(struct notifier_block *self,
    return NOTIFY_DONE;

    switch (cmd) {
    - case DIE_NMI:
    case DIE_NMI_IPI:
    break;
    case DIE_NMIUNKNOWN:
    diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
    index cfe4faa..e0132bf 100644
    --- a/arch/x86/oprofile/nmi_int.c
    +++ b/arch/x86/oprofile/nmi_int.c
    @@ -64,7 +64,6 @@ static int profile_exceptions_notify(struct notifier_block *self,
    int ret = NOTIFY_DONE;

    switch (val) {
    - case DIE_NMI:
    case DIE_NMI_IPI:
    if (ctr_running)
    model->check_ctrs(args->regs, &__get_cpu_var(cpu_msrs));
    --
    1.7.1.1


    > >
    > > What are you running to create the problem? I can try and duplicate
    > > it here.
    >
    > It happens easily here - just running something like:
    >
    > perf record -g ./hackbench 10
    >
    > a couple of times triggers it. Note, unlike with the earlier bug, the
    > NMIs are not permanently 'stuck' - and everything continues working.
    > Obviously the messages are nasty looking so this is a regression we need
    > to fix.
    >
    > Thanks,
    >
    > Ingo
    >

    --
    Advanced Micro Devices, Inc.
    Operating System Research Center



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