From: Kent Overstreet <koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 04/11] cgroup: use kzalloc() and list_del_init()
Date: Wed, 12 Jun 2013 19:52:02 -0700
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Christoph Lameter <cl-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>

On Wed, Jun 12, 2013 at 07:48:59PM -0700, Tejun Heo wrote:
> On Wed, Jun 12, 2013 at 07:43:10PM -0700, Kent Overstreet wrote:
> > list_del() does do poisoning - and list debugging is cheaper to enable
> > than full slab debugging.
> 
> Ah, right, now we have DEBUG_LIST.  Completely forgot about that.  I
> don't think the cost difference matters that much as long as there are
> enough people running with slab debugging, but, yeah, with DEBUG_LIST,
> leaving list_del() alone would actually be better.  I'll drop that
> part.

I can't remember if it was Fedora or RH (or both?) but in one of those
they actually leave it enabled in their production kernels. Someone was
blogging about the bugs it found...