linux-kernel - Re: [GIT BISECT] BUG kmalloc-8192: Object already free from kmem_cache

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Date:	Sun, 13 Sep 2009 19:11:33 -0400
From:	Eric Paris <eparis@...hat.com>
To:	cl@...ux-foundation.org
Cc:	dfeng@...hat.com, penberg@...helsinki.fi, mingo@...e.hu,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [GIT BISECT] BUG kmalloc-8192: Object already free from
 kmem_cache_destroy

On Sun, 2009-09-13 at 14:33 -0400, Eric Paris wrote:
> 2a38a002fbee06556489091c30b04746222167e4 is first bad commit
> commit 2a38a002fbee06556489091c30b04746222167e4
> Author: Xiaotian Feng <dfeng@...hat.com>
> Date:   Wed Jul 22 17:03:57 2009 +0800
> 
>     slub: sysfs_slab_remove should free kmem_cache when debug is enabled
>     
>     kmem_cache_destroy use sysfs_slab_remove to release the kmem_cache,
>     but when CONFIG_SLUB_DEBUG is enabled, sysfs_slab_remove just release
>     related kobject, the whole kmem_cache is missed to release and cause
>     a memory leak.
>     
>     Acked-by: Christoph Lameer <cl@...ux-foundation.org>
>     Signed-off-by: Xiaotian Feng <dfeng@...hat.com>
>     Signed-off-by: Pekka Enberg <penberg@...helsinki.fi>
> 
> CONFIG_SLUB_DEBUG=y
> CONFIG_SLUB=y
> CONFIG_SLUB_DEBUG_ON=y
> # CONFIG_SLUB_STATS is not set

I also had problems destroying a kmem_cache in a security_initcall()
function which had a different backtrace (it's what made me create the
module and bisect.)   So be sure to let me know what you find so I can
be sure that we fix that place as well   (I believe that was a kref
problem rather than a double free)

-Eric

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