Date: Fri, 23 Sep 2005 01:09:39 -0700 (PDT)
Message-Id: <20050923.010939.11256142.davem@davemloft.net>
To: nickpiggin@yahoo.com.au
Cc: ioe-lkml@rameria.de, linux-kernel@vger.kernel.org, clameter@engr.sgi.com
Subject: Re: making kmalloc BUG() might not be a good idea
From: "David S. Miller" <davem@davemloft.net>
In-Reply-To: <4333B588.9060503@yahoo.com.au>
References: <4333A109.2000908@yahoo.com.au>
	<200509230909.54046.ioe-lkml@rameria.de>
	<4333B588.9060503@yahoo.com.au>
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From: Nick Piggin <nickpiggin@yahoo.com.au>
Date: Fri, 23 Sep 2005 17:58:00 +1000

> Then you'll get people not enabling it on real workloads, or
> tuning it off if it bugs them. No, the point of having a WARN
> there is really for people like SGI to detect a few rare failure
> cases when they first boot up their 1024+ CPU systems. It is not
> going to spam anyone's logs (and if it does it *needs* fixing).

SGI (and people "like" them) can't enable a debug option when bringing
up new changes for the first time on that huge system?  Why is this?

What in the world are all these CONFIG_*DEBUG* options for then?
They are there for "I'm doing something radically new, or my new
change isn't working, therefore I need more debugging than usual."

We want it to spam the logs, sure, during _development_.  We don't
want it on production systems where any kind of downtime is a very
serious problem.  Rate limited, maybe, but not for every call as
that's simply asking for trouble.

This is why we have things like net_ratelimit() in the networking btw.
It's there so you can't remotely spam someone's logs just becuase you
figured out the "bug of the week" magic packet that erroneously
generates a huge number of log messages.

If we know how to make certain classes of bugs non-lethal, we should
do so because there will always be bugs. :-)  This change makes
previously non-lethal bugs potentially kill the machine.
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