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Message-Id: <1186397939.28655.63.camel@johannes.berg>
Date:	Mon, 06 Aug 2007 12:58:59 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Oleg Nesterov <oleg@...sign.ru>
Cc:	Trond Myklebust <trond.myklebust@....uio.no>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Marc Dietrich <Marc.Dietrich@...physik.uni-giessen.de>,
	Neil Brown <neilb@...e.de>, nfs@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [NFS] 2.6.23-rc1-mm2
On Mon, 2007-08-06 at 14:53 +0400, Oleg Nesterov wrote:
> But this makes ->lockdep_map meaningless? We always take wq->lockdep_map
> for reading, now we can't detect deadlocks.
> 
> 	read_lock(A);
> 	lock(B);
> 
> vs
> 	lock(B);
> 	read_lock(A);
> 
> is valid, kernel/lockdep.c should not complain.
Ah, hmm. Good point, I guess you can always have multiple read locks.
Then we'd have to make a new parameter or such to get rid of the
recursive locking try message. But if you want to deprecate the API
anyway then this is a good way to find it.
johannes
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