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SubjectRe: [PATCH -mm] oprofile: BUG: using smp_processor_id() in preemptible code

* 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?

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;

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