From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
Stephane Eranian <eranian@google.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>, Jiri Olsa <jolsa@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: BUG: using smp_processor_id() in preemptible [00000000] code: asm/8267
Date: Tue, 26 Mar 2013 19:34:52 +0100 [thread overview]
Message-ID: <20130326183452.GC27518@pd.tnic> (raw)
In-Reply-To: <20130324155924.GB4866@pd.tnic>
On Sun, Mar 24, 2013 at 04:59:24PM +0100, Borislav Petkov wrote:
> On Sun, Mar 24, 2013 at 12:55:56PM +0100, Borislav Petkov wrote:
> > Hi,
> >
> > so I was tracing a small .c program like so:
> >
> > $ ./perf record ~/test/asm
> >
> > and here's what got spewed in dmesg. Kernel is plain -rc4. Any pending
> > fixes in tip I should try?
> >
> > [ 3700.194208] BUG: using smp_processor_id() in preemptible [00000000] code: asm/8333
> > [ 3700.194226] caller is perf_event_task_ctx+0x55/0x140
>
> Ok, here's the call stack I was able to reconstruct:
>
> perf_event_exit_task()
> |->perf_event_exit_task_context()
> |-> perf_event_task()
> |-> perf_event_task_event()
> |-> perf_event_task_ctx()
> |-> perf_event_task_match()
> |-> event_filter_match()
> |-> smp_processor_id() -> debug_smp_processor_id()
Ok, jolsa just rootcaused it: It is caused by
d610d98b5de6860feb21539726e9af7c9094151c calling perf_event_task_ctx()
outside of the preempt-safe protection.
There's a straightforward fix below, what to people think?
--
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7b4a55d41efc..f3bb3384a106 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4455,8 +4455,11 @@ static void perf_event_task_event(struct perf_task_event *task_event)
next:
put_cpu_ptr(pmu->pmu_cpu_context);
}
+
+ preempt_disable();
if (task_event->task_ctx)
perf_event_task_ctx(task_event->task_ctx, task_event);
+ preempt_enable();
rcu_read_unlock();
}
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2013-03-26 18:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-24 11:55 BUG: using smp_processor_id() in preemptible [00000000] code: asm/8267 Borislav Petkov
2013-03-24 15:59 ` Borislav Petkov
2013-03-26 18:34 ` Borislav Petkov [this message]
2013-03-27 6:02 ` Namhyung Kim
2013-03-27 9:49 ` Borislav Petkov
2013-03-27 10:42 ` Jiri Olsa
2013-03-27 14:09 ` Peter Zijlstra
2013-03-27 16:31 ` Borislav Petkov
2013-04-30 15:27 ` [RFCv2] " Jiri Olsa
2013-03-27 13:15 ` Joerg Roedel
2013-03-27 14:17 ` Peter Zijlstra
2013-03-27 14:37 ` Paul E. McKenney
2013-03-27 16:34 ` Joerg Roedel
2013-03-27 16:38 ` Borislav Petkov
2013-03-27 18:04 ` Paul E. McKenney
2013-03-27 19:07 ` Borislav Petkov
2013-03-27 19:20 ` Borislav Petkov
2013-03-27 19:22 ` Paul E. McKenney
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