linux-kernel - Re: [PATCH 0/4] coredump: core dump masking support v3

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Message-ID: <20070226120154.GD3386@elf.ucw.cz>
Date:	Mon, 26 Feb 2007 13:01:54 +0100
From:	Pavel Machek <pavel@....cz>
To:	David Howells <dhowells@...hat.com>
Cc:	Markus Gutschke <markus@...gle.com>,
	"Kawai, Hidehiro" <hidehiro.kawai.ez@...achi.com>,
	Andrew Morton <akpm@...l.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	Robin Holt <holt@....com>, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <soshima@...hat.com>
Subject: Re: [PATCH 0/4] coredump: core dump masking support v3


> > While I am sure you could construct scenarios where this would happen,
> > realistically the only one I have run into were stack overflows, and they can
> > be handled by carefully setting up an alternate stack for signal handlers --
> > just make sure the entire stack is already dirtied before you run out of
> > memory (or, turn of overcommitting).
> 
> Duff SIGSEGV or SIGBUS signal handlers are just as realistic.  All that takes
> is for someone to make a programming error.  Remember: error paths are the
> least frequently tested.
> 
> And any time you say "by carefully setting up" you can guarantee someone's
> going to do it wrong.

By same argument, we should just give up the coredumping in kernel. It
is rarely tested, so someone will just get it wrong.

Remember: we are having people with huge apps, and therefore huge
coredumps. They want to hack a kernel in ugly way to make their dumps
smaller.

...but there's better solution for them, create (& debug) userland
coredumping library. No need to hack a kernel.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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