Subject: Re: Fwd: [bug] as_merged_requests(): possible recursive locking
	detected
From: Nikanth Karthikesan <knikanth@suse.de>
To: Jens Axboe <jens.axboe@oracle.com>, Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <47A35177.BANGALORE.BLR.100.174746A.1.1085C.1@1:7.BANGALORE.BLR.100.0.1.0.1@16>
References: <20080131221436.GA3760@elte.hu>
	 <20080201084056.GH15220@kernel.dk> <20080201104537.GA27178@elte.hu>
	 <20080201104733.GM15220@kernel.dk> <20080201110123.GF27178@elte.hu>
	 <20080201112238.GN15220@kernel.dk>
	 <47A35177.BANGALORE.BLR.100.174746A.1.1085C.1@1:7.BANGALORE.BLR.100.0.1.0.1@16>
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Date: Fri, 01 Feb 2008 17:23:42 +0530
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> > am i right that lockdep complained about real lockup potential here?
> > (i.e. it caught a real bug) So there's no need to change anything on the
> > lockdep side, right?
> 
> Right, no bug in lockdep, the locking code and swap_io_context() are
> just screwed up.
> 

I doubt a bug in lockdep. Here we just swap the pointers but use the
addresses themselves to order locks. And we do not change the
contents(lock) in those addresses. So it could be a lockdep bug.

Thanks
Nikanth Karthikesan


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