Date: Mon, 1 Jun 2009 21:14:50 +0200
From: Andi Kleen <andi@firstfloor.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>, paul@mad-scientist.net,
       Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.kernel.org,
       stable@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Roland McGrath <roland@redhat.com>
Subject: Re: [PATCH] coredump: Retry writes where appropriate
Message-ID: <20090601191449.GW1065@one.firstfloor.org>
References: <1243748019.7369.319.camel@homebase.localnet> <20090531111851.07eb1df3@lxorguk.ukuu.org.uk> <20090601161234.GA10486@redhat.com> <1243877766.8547.38.camel@psmith-ubeta.netezza.com> <20090601184934.1fc54411@lxorguk.ukuu.org.uk> <1243881544.8547.66.camel@psmith-ubeta.netezza.com> <20090601200232.078aacbb@lxorguk.ukuu.org.uk> <20090601190914.GV1065@one.firstfloor.org> <20090601200630.6b18bcc1@lxorguk.ukuu.org.uk>
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On Mon, Jun 01, 2009 at 08:06:30PM +0100, Alan Cox wrote:
> On Mon, 1 Jun 2009 21:09:14 +0200
> Andi Kleen <andi@firstfloor.org> wrote:
> 
> > On Mon, Jun 01, 2009 at 08:02:32PM +0100, Alan Cox wrote:
> > > > If a program seems to be unresponsive the user could ^C, without
> > > > realizing that it was really dumping core.  Now when they are asked to
> > > > produce the core so the problem can be debugged, they can't do it.  Or,
> > > 
> > > and get their prompt back, which is probably why they are banging ^C. If
> > > they didn't want their prompt back at that point they'd still be
> > > wondering why nothing was occuring at the point it said (core dumped)
> > 
> > Maybe we need a background core dump?
> 
> You can pretty much implement that via the pipe handler if you care. Just
> buffer aggressively.
> 
> For the general case however programs assume that when wait() returns
> indicating the core dump occurred that they can immediately access the
> dump (eg bug-buddy in Gnome)

Then set a advisory lock on the dump... no seriously:

With full signal handling during dump they would probably get a lot of time
a partial dump at best, because it's common to set signals in a row. 
I agree with Paul on that that that is unfortunate at best.

Perhaps that's something that just needs a sysctl.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.
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