Subject: Re: [PATCH] slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU

From: Eric Dumazet <[email-masked]>
Date: Thu, 03 Sep 2009 21:56:04 +0200

Pekka Enberg a écrit :
> On Thu, Sep 3, 2009 at 5:18 PM, Eric Dumazet<[email-masked]> wrote:
>> Here is the second patch (RCU thing). Stable candidate
>>
>> [PATCH] slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU
>>
>> kmem_cache_destroy() should call rcu_barrier() *after* kmem_cache_close()
>> and *before* sysfs_slab_remove() or risk rcu_free_slab()
>> being called after kmem_cache is deleted (kfreed).
>>
>> rmmod nf_conntrack can crash the machine because it has to
>> kmem_cache_destroy() a SLAB_DESTROY_BY_RCU enabled cache.
> 
> Do we have a bugzilla URL for this?

Well, I can crash my 2.6.30.5 machine just doing rmmod nf_conntrack

(You'll need CONFIG_SLUB_DEBUG_ON or equivalent)

Original Zdenek report : http://thread.gmane.org/gmane.linux.kernel/876016/focus=876086

> 
>> Reported-by: Zdenek Kabelac <[email-masked]>
>> Signed-off-by: Eric Dumazet <[email-masked]>
>> Acked-by: Paul E. McKenney <[email-masked]>
> 
> OK, this is in for-next now and queued for 2.6.31. If you guys want to
> fix this in a different way, lets do that in 2.6.32.

Seems the right thing IMHO
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