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Message-ID: <1326632384.11711.3.camel@lappy>
Subject: Re: Hung task when calling clone() due to netfilter/slab
From: Sasha Levin <levinsasha928@gmail.com>
Date: Sun, 15 Jan 2012 14:59:44 +0200
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To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dave Jones <davej@redhat.com>, davem <davem@davemloft.net>, Pekka Enberg <penberg@kernel.org>, Christoph Lameter <cl@linux-foundation.org>, Matt Mackall <mpm@selenic.com>, kaber@trash.net, pablo@netfilter.org, linux-kernel <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, netfilter-devel@vger.kernel.org, netdev <netdev@vger.kernel.org>

On Sat, 2012-01-14 at 18:10 +0100, Eric Dumazet wrote:
> Apparently SLUB calls sysfs_slab_add() from kmem_cache_create() while
> still holding slub_lock.
> 
> So if the task launched needs to "cat /proc/slabinfo" or anything
> needing slub_lock, its a deadlock.

I've made the following patch to test it, It doesn't look like it's the correct solution, but it verifies that the problem is there (it works well with the patch).

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