linux-kernel - Re: [Bug #13319] Page allocation failures with b43 and p54usb

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Date:	Tue, 30 Jun 2009 13:25:57 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Pekka Enberg <penberg@...helsinki.fi>
cc:	Larry Finger <Larry.Finger@...inger.net>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	Johannes Berg <johannes@...solutions.net>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [Bug #13319] Page allocation failures with b43 and p54usb

On Tue, 30 Jun 2009, Pekka Enberg wrote:

> On Tue, Jun 30, 2009 at 10:47 AM, David Rientjes<rientjes@...gle.com> wrote:
> > I don't think CONFIG_SLUB_DEBUG_ON is generally the configuration used in
> > the real world.
> 
> It is, hence the epic bug report that's eaten too many man hours
> already! Look, we encourage _testers_ to turn all as much as debugging
> options as possible so we catch bugs early. That why the only sane
> defaults are the ones that don't cause other problems!
> 

I feel that asking a user to add a command line parameter such as 
`slub_debug=A' in addition to CONFIG_SLUB_DEBUG_ON will likely lead to 
less testing coverage and bugs going unreported.  CONFIG_SLUB_DEBUG_ON is 
not something that a distro is going to enable or would be used in a 
production environment, it's something that's used to debug slub and/or 
slab allocations either during the development of new kernel code or when 
an underlying problem is realized.

> I don't know why you want to argue this. It's simply not an option to
> say "stupid user, fix your config" in core code like the slab
> allocator. Enabling CONFIG_SLUB_DEBUG_ON is a very reasonable thing to
> do when you are a tester looking for bugs.
> 

Quite the contrary, I agree completely with the above, and that's why I'm 
arguing for full debugging to be enabled when a well-defined configuration 
option is enabled.  I simply don't believe that such debugging should be 
coupled with a command line option to be fully activated for all caches.
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