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Message-ID: <4333B588.9060503@yahoo.com.au>
Date: Fri, 23 Sep 2005 17:58:00 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Ingo Oeser <ioe-lkml@rameria.de>
CC: linux-kernel@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
       clameter@engr.sgi.com
Subject: Re: making kmalloc BUG() might not be a good idea
References: <20050922.231434.07643075.davem@davemloft.net> <4333A109.2000908@yahoo.com.au> <200509230909.54046.ioe-lkml@rameria.de>
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Ingo Oeser wrote:
> Hi,
> 
> On Friday 23 September 2005 08:30, Nick Piggin wrote:
> 
>>David S. Miller wrote:
>>
>>>I'm sort-of concerned about this change:
>>>
>>>   [PATCH] __kmalloc: Generate BUG if size requested is too large.
>>>
>>>it opens a can of worms, and stuff that used to generate
>>>-ENOMEM kinds of failures will now BUG() the kernel.
>>
>>Making it WARN might be a good compromise.
> 
> 
> Which has the potential to spam the logs with a user triggerable event
> without even killing the responsible process.
> Same problem, just worse.
> 

As opposed to potentially taking the system down? I don't
think so.

> I could live with a solution that enables it based on a config.
> 

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).

What you don't want is to kill the responsible process, because
at that point they're deep in the kernel, probably holding other
locks and resources.

-- 
SUSE Labs, Novell Inc.

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