Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint

From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	lkml <linux-kernel@vger.kernel.org>,
	systemtap <systemtap@sources.redhat.com>,
	DLE <dle-develop@lists.sourceforge.net>,
	Oleg Nesterov <oleg@redhat.com>,
	Roland McGrath <roland@redhat.com>,
	Jason Baron <jbaron@redhat.com>
Subject: Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint
Date: Sat, 5 Dec 2009 16:18:38 +0900	[thread overview]
Message-ID: <2f11576a0912042318u4c9c90cetb4ce136e977c2596@mail.gmail.com> (raw)
In-Reply-To: <20091202204637.25408.41195.stgit@dhcp-100-2-132.bos.redhat.com>

2009/12/3 Masami Hiramatsu <mhiramat@redhat.com>:
> Add signal coredump tracepoint which shows signal number,
> mm->flags, limits, pointer to file structure 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.

AFAIK, not-dumped case is important than dump successful case.
IOW, admin need to know why the crashed process was not dumped.

This tracepoint doesn't cover all failure case. especially
binfmt->core_dump() et.al.
IOW, this tracepoint seems too specialized piped-coredump feature.

What do you think this tracepoint's use case?