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Re: systemtap 2.2.1 installcheck => kernel BUG at .. kprobes.c:707


(2013/05/22 23:21), Frank Ch. Eigler wrote:
> Hi, Masami -
> 
>> I've found the root cause of this bug at last.
> 
> Thanks for looking into it!
> 
>> [...]
>> This shouldn't happen if the probe unregistration is done AFTER
>> kprobes_module_callback is called (because at that time the op
>> is gone), and kprobe-tracer does it.
>> So, ftrace never gets this bug, but systemtap does.
> 
> I don't quite understand.  In systemtap, as per runtime/transport/transport.c,
> we use a notifier priority of 1 for the _stp_module_notifier, so that we get
> notified after the kprobes_module_callback.  I believe this behavior matches
> ftrace.

OK, even though, a probe have been removed right before the target module
is unloaded, it also hits the same problem. So, could you try to apply
the patch I posted on LKML and this ML yesterday?
https://lkml.org/lkml/2013/5/22/172

I hope it fixed the bug ...

Thank you,

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com



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