linux-kernel - Re: [PATCH] coredump: Retry writes where appropriate

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Message-ID: <20090601191449.GW1065@one.firstfloor.org>
Date:	Mon, 1 Jun 2009 21:14:50 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Andi Kleen <andi@...stfloor.org>, paul@...-scientist.net,
	Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
	stable@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Roland McGrath <roland@...hat.com>
Subject: Re: [PATCH] coredump: Retry writes where appropriate

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@...stfloor.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@...ux.intel.com -- Speaking for myself only.
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