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Date: Mon, 24 Mar 2014 10:27:35 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Takao Indoh <indou.takao@jp.fujitsu.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Ingo Molnar <mingo@redhat.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
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        "David S. Miller" <davem@davemloft.net>, linux-kernel@vger.kernel.org,
        Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: ftrace/kprobes: Warning when insmod two modules
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On Mon, 24 Mar 2014 20:26:05 +0900
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:

 
> Thank you for reporting with this pretty backtrace :)
> Steven, I think this is not the kprobe bug but ftrace (and perhaps, module).
> 
> If the ftrace can set loading module text read only before the module subsystem
> expected, I think it should be protected by the module subsystem itself
> (e.g. set_all_modules_text_ro(rw) skips the modules which is MODULE_STATE_COMING)
> 

I have to admit. I never thought about having the module init code
enabling ftrace :-)

Yeah, it looks like we need to handle this case. I'll take a look into
it.

Thanks for the report,

-- Steve