[PATCH v4] [RFC] tracepoint: Add signal coredump tracepoint

[KOSAKI Motohiro]

> Add signal coredump tracepoint which shows signal number,
> mm->flags, core file size limitation, the result of
> coredump, and core file name.
> 
> This tracepoint requirement comes mainly from the viewpoint of
> administrators. Since now we have introduced many coredump
> configurations (e.g. dumpable, coredump_filter, core_pattern,
> etc) and some of them can be modified by users, it will be hard
> to know what was actually dumped (or not dumped) after some
> problem happened on the system. For example, a process didn't
> generated core, coredump doesn't have some sections, etc.
> In those cases, the coredump tracepoint can help us to know
> why the core file is so big or small, or not generated, by
> recording all configurations for all processes on the system.
> That will reduce system-administration cost.
> 
> Changes in v4:
>  - Rename limit trace-argument to core_size_limit, because
>    of user friendly output.

Looks good to me.