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Date: Tue, 17 Jan 2012 10:04:38 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
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To: Eric Dumazet <eric.dumazet@gmail.com>
cc: Sasha Levin <levinsasha928@gmail.com>, Dave Jones <davej@redhat.com>,
        davem <davem@davemloft.net>, Pekka Enberg <penberg@kernel.org>,
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        netdev <netdev@vger.kernel.org>
Subject: Re: Hung task when calling clone() due to netfilter/slab
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On Tue, 17 Jan 2012, Eric Dumazet wrote:

> Thanks !
>
> Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

That may not be the end of it. Slub also calls sysfs from sysfs_add_alias
while holding slub_lock.

If sysfs allows user space stuff to run then you cannot really hold any
locks. How is one supposed to sync adding pointers to sysfs structures in
subsystems? Drop all locks and then recheck the memory structures after
the sysfs function returns? Awkward.