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Date: Mon, 12 Mar 2007 14:51:12 +0100
From: Ingo Molnar <mingo@elte.hu>
To: "Michael S. Tsirkin" <mst@mellanox.co.il>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Roland Dreier <roland.list@gmail.com>,
       Tziporet Koren <tziporet@mellanox.co.il>,
       Roland Dreier <rdreier@cisco.com>, general@lists.openfabrics.org,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: lockdep question (was Re: IPoIB caused a kernel: BUG: softlockup detected on CPU#0!)
Message-ID: <20070312135112.GA18158@elte.hu>
References: <45E552FC.4040305@mellanox.co.il> <f8ca0a150703030937u61bcd9aj200415b76c00d151@mail.gmail.com> <20070311135051.GA31985@mellanox.co.il> <1173626719.5182.10.camel@lappy> <20070311161231.GC13817@mellanox.co.il> <20070311184819.GA2567@elte.hu> <20070312132826.GB20549@mellanox.co.il>
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* Michael S. Tsirkin <mst@mellanox.co.il> wrote:

> > could you turn on CONFIG_SLAB_DEBUG as well?
> > 
> > that should catch certain types of use-after-free accesses, and 
> > lockdep will also warn if a still locked object is freed.
> 
> Hmm, no, this does not look like use-after-free. I enabled 
> CONFIG_SLAB_DEBUG, and I still see the same message, so the memory was 
> not overwritten by slab debugger.

that's still not conclusive - the memory might not have been allocated 
by slab again to detect it. Your magic-number check definitely shows 
some sort of corruption going on, right?

	Ingo