linux-kernel - Re: [RFC] [PATCH] cpuset operations causes Badness at mm/slab.c:777 warning

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Message-ID: <466081DE.70205@goop.org>
Date:	Fri, 01 Jun 2007 13:30:22 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Srinivasa Ds <srinivasa@...ibm.com>
CC:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Dinakar Guniguntala <dino@...ibm.com>, pj@....com,
	simon.derr@...l.net, clameter@....com,
	clameter@...ulhu.engr.sgi.com, rientjes@...gle.com
Subject: Re: [RFC] [PATCH] cpuset operations causes Badness at mm/slab.c:777
 warning

Srinivasa Ds wrote:
> ---
>  kernel/cpuset.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> Index: linux-2.6.22-rc3/kernel/cpuset.c
> ===================================================================
> --- linux-2.6.22-rc3.orig/kernel/cpuset.c
> +++ linux-2.6.22-rc3/kernel/cpuset.c
> @@ -1741,6 +1741,13 @@ static int cpuset_tasks_open(struct inod
>  	 * show up until sometime later on.
>  	 */
>  	npids = atomic_read(&cs->count);
> +	if (!npids) {
> +		ctr->buf = NULL;
> +		ctr->bufsz = 0;
> +		file->private_data = ctr;
> +		return 0;
> +	}
> +
>   

I think this is a good example of why having to special-case kmalloc(0)
is a bad idea.  The original code was straightforward and, barring
silliness, should be completely correct with npids==0.  This new code
does nothing other than make things more complex.

    J
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