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SubjectRe: [PATCH -mm] oprofile: BUG: using smp_processor_id() in preemptible code
On 22.09.08 12:28:34, Ingo Molnar wrote:
>
> * Ingo Molnar <mingo@elte.hu> wrote:
>
> > > + local_irq_save(flags);
> > > __get_cpu_var(switch_index) = 0;
> > > + local_irq_restore(flags);
> >
> > either use __raw_get_cpu_var() if we are for sure not preemptible
> > here, or fix the preemption status of this codepath.
>
> i've applied the patch below instead to tip/oprofile - agreed?

Acked-by: Robert Richter <robert.richter@amd.com>

>
> Ingo
>
> ------------>
> From 45f197ade73ba95681b9803680c75352fc0a1c0a Mon Sep 17 00:00:00 2001
> From: Andrea Righi <righi.andrea@gmail.com>
> Date: Sat, 20 Sep 2008 12:58:40 +0200
> Subject: [PATCH] x86, oprofile: BUG: using smp_processor_id() in preemptible code
>
> Add __raw access before setting per cpu variable switch_index, to avoid
> the following BUG:
>
> [ 449.166827] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/6998
> [ 449.166848] caller is op_nmi_init+0xf0/0x2b0 [oprofile]
> [ 449.166855] Pid: 6998, comm: modprobe Not tainted 2.6.27-rc5-mm1 #29
> [ 449.166860] Call Trace:
> [ 449.166872] [<ffffffff80362d67>] debug_smp_processor_id+0xd7/0xe0
> [ 449.166887] [<ffffffffa00181c0>] op_nmi_init+0xf0/0x2b0 [oprofile]
> [ 449.166902] [<ffffffffa0018000>] oprofile_init+0x0/0x60 [oprofile]
> [ 449.166915] [<ffffffffa00180a9>] oprofile_arch_init+0x9/0x30 [oprofile]
> [ 449.166928] [<ffffffffa001801e>] oprofile_init+0x1e/0x60 [oprofile]
> [ 449.166937] [<ffffffff8020903b>] _stext+0x3b/0x160
> [ 449.166946] [<ffffffff80477985>] __mutex_unlock_slowpath+0xe5/0x190
> [ 449.166955] [<ffffffff80262c1a>] trace_hardirqs_on_caller+0xca/0x140
> [ 449.166965] [<ffffffff8026f7fc>] sys_init_module+0xdc/0x210
> [ 449.166972] [<ffffffff8020b7cb>] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
> Acked-by: Robert Richter <robert.richter@amd.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> arch/x86/oprofile/nmi_int.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
> index fb4902b..4108d02 100644
> --- a/arch/x86/oprofile/nmi_int.c
> +++ b/arch/x86/oprofile/nmi_int.c
> @@ -551,7 +551,7 @@ int __init op_nmi_init(struct oprofile_operations *ops)
> }
>
> /* default values, can be overwritten by model */
> - __get_cpu_var(switch_index) = 0;
> + __raw_get_cpu_var(switch_index) = 0;
> ops->create_files = nmi_create_files;
> ops->setup = nmi_setup;
> ops->shutdown = nmi_shutdown;
>

--
Advanced Micro Devices, Inc.
Operating System Research Center
email: robert.richter@amd.com



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