From: Randy Dunlap <randy.dunlap@oracle.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: 2.6.33 GP fault only when built with tracing
Date: Fri, 19 Mar 2010 11:22:07 -0700 [thread overview]
Message-ID: <4BA3C0CF.6070005@oracle.com> (raw)
In-Reply-To: <20100319005901.GB23020@Krystal>
On 03/18/10 17:59, Mathieu Desnoyers wrote:
> * Steven Rostedt (rostedt@goodmis.org) wrote:
>> On Thu, 2010-03-18 at 16:26 -0700, Randy Dunlap wrote:
>>> I can build/boot 2.6.33 with CONFIG_TRACE/TRACING disabled successfully,
>>> but when I enable lots of tracing config options and then boot with
>>> ftrace=nop on the kernel command line, I see a GP fault when the parport &
>>> parport_pc modules are loading/initializing.
>>
>> Do you see it without adding the "ftrace=nop"? The only thing that
>> should do is expand the ring buffer on boot up.
>>
>>>
>>> It happens in drivers/parport/share.c::parport_register_device(), when that
>>> function calls try_module_get().
>>>
>>> If I comment out the trace_module_get() calls in include/linux/module.h,
>>> the kernel boots with no problems.
>>
>>
>> Interesting. Well, trace_module_get() is a TRACE_EVENT tracepoint. But
>> should be disabled here. It may be something to do with DEFINE_TRACE.
>>
>> (added Mathieu to Cc since he wrote that code)
>
> can you try replacing the "local_read(__module_ref_addr(module, cpu))" argument
> with "0" ?
Yes, that boots with no problems.
> Arguments with side-effects are not skipped by the jump over disabled
> instrumentation. This is why we should do that part within the probe declaration
> in the TRACE_EVENT macros.
>
> But if we find out that the problem really is this argument, then it should be
> fixed, because something would be wrong with it (just moving it to TRACE_EVENT
> is not a proper solution).
>
> Thanks,
>
> Mathieu
--
~Randy
next prev parent reply other threads:[~2010-03-19 18:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-18 23:26 2.6.33 GP fault only when built with tracing Randy Dunlap
2010-03-18 23:55 ` Steven Rostedt
2010-03-19 0:08 ` Randy Dunlap
2010-03-19 0:59 ` Mathieu Desnoyers
2010-03-19 18:22 ` Randy Dunlap [this message]
2010-03-19 18:46 ` Mathieu Desnoyers
2010-03-23 15:26 ` Randy Dunlap
2010-03-24 1:20 ` Mathieu Desnoyers
2010-03-24 1:42 ` Li Zefan
2010-03-24 20:21 ` Randy Dunlap
2010-03-24 20:31 ` Steven Rostedt
2010-03-20 0:12 ` Randy Dunlap
2010-03-19 0:01 ` Frederic Weisbecker
2010-03-19 2:15 ` Steven Rostedt
2010-03-19 16:10 ` Randy Dunlap
2010-03-24 2:57 ` [PATCH 1/3] tracing: Reduce overhead of module tracepoints Li Zefan
2010-03-24 2:58 ` [PATCH 2/3] tracing: Convert some signal events to DEFINE_TRACE Li Zefan
2010-03-24 3:07 ` Steven Rostedt
2010-03-24 3:17 ` Masami Hiramatsu
2010-04-02 19:03 ` [tip:tracing/core] " tip-bot for Li Zefan
2010-03-24 2:58 ` [PATCH 3/3] tracing: Update comments Li Zefan
2010-03-24 3:07 ` Steven Rostedt
2010-04-02 19:04 ` [tip:tracing/core] " tip-bot for Li Zefan
2010-03-24 3:05 ` [PATCH 1/3] tracing: Reduce overhead of module tracepoints Steven Rostedt
2010-03-24 10:24 ` Mathieu Desnoyers
2010-03-24 23:41 ` Randy Dunlap
2010-03-27 2:03 ` [tip:tracing/urgent] tracing: Remove side effect from module tracepoints that caused a GPF tip-bot for Li Zefan
2010-03-27 4:10 ` Mathieu Desnoyers
2010-03-27 4:23 ` Steven Rostedt
2010-04-02 19:04 ` [tip:tracing/core] " tip-bot for Li Zefan
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