RE: instrumenting vs. module loading

["Lynch, Rusty" <rusty dot lynch at intel dot com>]

>Ananth N Mavinakayanahalli wrote:
>> Ananth N Mavinakayanahalli wrote:
>>
>>> Frank Ch. Eigler wrote:
>>>
>>> I don't have much idea about in kernel details of module loading and
>>> unloading, but I'd imagine we'll encounter "interesting" issues if a
>>> different module is loaded in the same text range with such a stray
>>> kprobe.
>>
>>
>> On more thought, we won't see any such issues - we won't have the
>> breakpoint hit at all - the whole text gets overlaid right?
>>
>> Doh! what was I thinking earlier.. need more coffee :-)
>>
>> Ananth
>>
>>
>>
>
>All is fine until the clean up code tries to unregister the kprobe and
>it scribbles over that location in memory which no longer has the
>breakpoint.
>
>-will

Or... the same memory is used to load a new module, and we end up
replacing an instruction with the old original instruction.  Can you
imagine if that didn't trigger a crash, but just some very subtle bug.

I think this could be solved in the unregistration.

    --rusty