Message-ID: <5230C405.8040108@gmail.com>
Date: Wed, 11 Sep 2013 15:27:01 -0400
From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
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To: Janani Venkataraman <jananive@linux.vnet.ibm.com>
CC: linux-kernel@vger.kernel.org,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>,
        Andi Kleen <andi@firstfloor.org>,
        Roland McGrath <roland@hack.frob.com>,
        Amerigo Wang <amwang@redhat.com>, Christoph Hellwig <hch@lst.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Masami Hiramatsu <mhiramat@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>, xemul@parallels.com,
        Oleg Nesterov <oleg@redhat.com>, Tejun Heo <tj@kernel.org>,
        avagin@openvz.org, gorcunov@openvz.org,
        James Hogan <james.hogan@imgtec.com>,
        Mike Frysinger <vapier@gentoo.org>,
        "Randy.Dunlap" <rdunlap@xenotime.net>, Eric Paris <eparis@redhat.com>,
        ananth@in.ibm.com, suzuki@in.ibm.com, aravinda@linux.vnet.ibm.com,
        tarundeep.singh@in.ibm.com, kosaki.motohiro@gmail.com
Subject: Re: RFD: Non-Disruptive Core Dump Infrastructure
References: <522472DA.4000702@linux.vnet.ibm.com> <5225A02B.6080901@linux.vnet.ibm.com>
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(9/3/13 4:39 AM), Janani Venkataraman wrote:
> Hello,
>
> We are working on an infrastructure to create a system core file of a specific
> process at run-time, non-disruptively. It can also be extended to a case where
> a process is able to take a self-core dump.
>
> gcore, an existing utility creates a core image of the specified process. It
> attaches to the process using gdb and runs the gdb gcore command and then
> detaches. In gcore the dump cannot be issued from a signal handler context as
> fork() is not signal safe and moreover it is disruptive in nature as the gdb
> attaches using ptrace which sends a SIGSTOP signal. Hence the gcore method
> cannot be used if the process wants to initiate a self dump.

Maybe I'm missing something. But why gcore uses c-level fork()? gcore need to
call pthread-at-fork handler? No. gcore need to flush stdio buffer? No.
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