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Date: Mon, 19 Mar 2012 11:31:47 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
X-X-Sender: cl@router.home
To: Sasha Levin <levinsasha928@gmail.com>
cc: Pablo Neira Ayuso <pablo@netfilter.org>, kaber@trash.net,
        davem@davemloft.net, Dave Jones <davej@redhat.com>,
        netfilter-devel@vger.kernel.org,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        netdev@vger.kernel.org
Subject: Re: netfilter: Hung task
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On Mon, 19 Mar 2012, Sasha Levin wrote:

> On Mon, Mar 19, 2012 at 3:56 PM, Christoph Lameter <cl@linux.com> wrote:
> > This is sually something causing memory corruption. Please enable
> > debugging to get backtrace that help to debutg this. CONFIG_SLUB_DEBUG_ON
> > will do the trick or passing "slub_debug" on the kernel command line.
>
> The kernel was compiled with SLUB_DEBUG_ON, there's nothing coming out
> of the slub before that hang message, nor after it.

Ok looking at the backtrace: This is kmem_cache_destroy and not the usual
failure following a pointer in alloc / free.

netfilter calls kmem_cache_destroy which calls into sysfs functions and
there the hang occurs.

Did you try to see if lockdep can detect any serialization problems ?

Is kmem_cache_destroy called with any locks held? Interrupts off?