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Date: Wed, 1 Oct 2014 14:57:57 +0800
From: Fengguang Wu <fengguang.wu@intel.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Ingo Molnar <mingo@kernel.org>, Jet Chen <jet.chen@intel.com>,
        Su Tao <tao.su@intel.com>, Yuanhan Liu <yuanhan.liu@intel.com>,
        LKP <lkp@01.org>, linux-kernel@vger.kernel.org
Subject: Re: [hw_breakpoint] WARNING: at kernel/trace/trace_kprobe.c:1393
 kprobe_trace_self_tests_init()
Message-ID: <20141001065757.GA17297@wfg-t540p.sh.intel.com>
References: <20140930074305.GA8090@wfg-t540p.sh.intel.com>
 <20140930175844.GA20922@redhat.com>
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Hi Oleg,

> > +-----------------------------------------------------------------------+------------+------------+------------------+
> > |                                                                       | 003002e04e | 8b4d801b2b | v3.17-rc7_093000 |
> > +-----------------------------------------------------------------------+------------+------------+------------------+
> > | boot_successes                                                        | 60         | 0          | 0                |
> > | boot_failures                                                         | 0          | 20         | 11               |
> > | WARNING:at_kernel/trace/trace_kprobe.c:kprobe_trace_self_tests_init() | 0          | 20         | 11               |
> > | backtrace:kprobe_trace_self_tests_init                                | 0          | 20         | 11               |
> > | backtrace:warn_slowpath_null                                          | 0          | 20         | 11               |
> > | backtrace:kernel_init_freeable                                        | 0          | 20         | 11               |
> > +-----------------------------------------------------------------------+------------+------------+------------------+
> >
> > [    4.188679] Testing kprobe tracing:
> > [    4.189810] Could not insert probe at kprobe_trace_selftest_target+0: -22
> 
> __register_trace_kprobe() fails.
> 
> No, I am very sure this can't be caused by the commit above. If nothing else,
> task_bp_pinned() changed by this commit is not even called in this case.

Sorry it is a bad bisect -- debug shows that CONFIG_FTRACE_STARTUP_TEST
is not enabled at all in the parent commit, which makes it boot success.
I'll fix this issue in my script and make the bisect stable.

Thanks,
Fengguang