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Date: Tue, 20 Feb 2001 09:11:04 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: Andrea Arcangeli <andrea@suse.de>
cc: Marcelo Tosatti <marcelo@conectiva.com.br>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: __lock_page calls run_task_queue(&tq_disk) unecessarily?
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On Tue, 20 Feb 2001, Andrea Arcangeli wrote:
> 
> Looks perfect. I'd also remove the `continue' from __lock_page, it's wake-one
> so it should get the wakeup only when it's time to lock the page down.

NO!

Even if it is wake-one, others may have claimed it before. There can be
new users coming in and doing a "trylock()" etc.

NEVER *EVER* think that "exclusive wait-queue" implies some sort of
critical region protection. An exlcusive wait-queue is _not_ a lock. It's
only an optimization heuristic.

		Linus

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