From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Jovi Zhangwei <jovi.zhangwei@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Oleg Nesterov <oleg@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"yrl.pp-manager.tt@hitachi.com" <yrl.pp-manager.tt@hitachi.com>
Subject: Re: Re: [BUG] 3.13-rc1 kernel crash when enable all tracepoints
Date: Tue, 26 Nov 2013 19:27:15 +0900 [thread overview]
Message-ID: <52947783.2040700@hitachi.com> (raw)
In-Reply-To: <52946261.8020408@hitachi.com>
(2013/11/26 17:57), Masami Hiramatsu wrote:
> (2013/11/26 16:20), Jovi Zhangwei wrote:
>> I'm not sure this relate with ftrace:function event, from the
>> crash log, it seems more like caused by lock events.
>>
>> Now I only enable lock events (lockdep compiled in my box), below
>> two commands both can crash system.
>
> That is not the lockdep, but the lockstat. :)
>
>>
>> #echo 1 > /sys/kernel/debug/tracing/events/lock/lock_acquire/enable
>> or.
>> #echo 1 > /sys/kernel/debug/tracing/events/lock/lock_release/enable
>>
>> According to the log, it seems like a recursion tracing bug.
>>
>> register lock event -> jump_label_update -> text_poke_bp ->
>> on_each_cpu -> local_apic_timer_interrupt -> ktime_get_update_offsets
>> -> lock_release
>
> OK, the problem is in the lock_acquire/release events.
Hm, it seems that the bug is caused because lock->name is NULL in
ftrace_raw_event_lock(_acquire). To allocate a buffer on ring_buffer,
ftrace_raw_event_##call tries to measure the length of lock->name
but it causes a memory access violation in ftrace_get_offsets_##call
because lock->name is NULL. :(
I could fix this by checking lock->name in include/trace/events/lock.h
e.g.
TP_STRUCT__entry(
__field(unsigned int, flags)
__string(name, lock->name ?: "NULL")
__field(void *, lockdep_addr)
),
TP_fast_assign(
__entry->flags = (trylock ? 1 : 0) | (read ? 2 : 0);
__assign_str(name, lock->name ?: "NULL");
__entry->lockdep_addr = lock;
),
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2013-11-26 10:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 4:38 [BUG] 3.13-rc1 kernel crash when enable all tracepoints Jovi Zhangwei
2013-11-26 6:33 ` Masami Hiramatsu
2013-11-26 7:20 ` Jovi Zhangwei
2013-11-26 8:57 ` Masami Hiramatsu
2013-11-26 10:27 ` Masami Hiramatsu [this message]
2013-11-26 7:26 ` (ltc-kernel 7837) " Masami Hiramatsu
2013-11-26 12:58 ` Steven Rostedt
2013-11-26 14:32 ` Shuah Khan
2013-11-26 14:44 ` Steven Rostedt
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