Re: [PATCH 2.6.12-rc4: resent] cpuset exit NULL dereference fix

[Simon Derr <Simon.Derr@bull.net>]

On Fri, 27 May 2005, Paul Jackson wrote:

> Andrew,
> 
> Resubmitting the same patch I submitted yesterday.  Simon Derr
> and I agree that we need this patch now to fix a kernel crash.
> 
> The potential scaling issues are theoretical at this time.
> When they become more real, we will be in a better position to
> consider more ambitious changes to cpuset locking and reference
> counting.
> 
> Meanwhile -- this patch is small, simple, and needed.
> 
> ===
> 
> There is a race in the kernel cpuset code, between the code
> to handle notify_on_release, and the code to remove a cpuset.
> The notify_on_release code can end up trying to access a
> cpuset that has been removed.  In the most common case, this
> causes a NULL pointer dereference from the routine cpuset_path.
> However all manner of bad things are possible, in theory at least.

> Signed-off-by: Paul Jackson <pj@sgi.com>
> 
> Index: 2.6-cpuset_path_fix/kernel/cpuset.c
> ===================================================================
> --- 2.6-cpuset_path_fix.orig/kernel/cpuset.c	2005-05-25 19:20:27.000000000 -0700
> +++ 2.6-cpuset_path_fix/kernel/cpuset.c	2005-05-26 00:50:32.000000000 -0700

OK for me.

Acked-by: Simon Derr <simon.derr@bull.net>

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