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

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Date:	Mon, 14 Sep 2009 11:41:43 +0800
From:	Danny Feng <dfeng@...hat.com>
To:	Eric Paris <eparis@...hat.com>
CC:	cl@...ux-foundation.org, 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 09/14/2009 07:11 AM, Eric Paris wrote:
> 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
>
>
>    
That's my fault... Please drop this patch, I didn't notice the free 
action in kobject release phase.. Thanks for point it out.
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