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Date: Sun, 25 Feb 2001 19:29:21 -0500 (EST)
From: Alexander Viro <viro@math.psu.edu>
To: Jens Axboe <axboe@suse.de>
cc: Nate Eldredge <neldredge@hmc.edu>, linux-kernel@vger.kernel.org
Subject: Re: 2.4.2-ac3: loop threads in D state
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On Mon, 26 Feb 2001, Jens Axboe wrote:

> On Sun, Feb 25 2001, Alexander Viro wrote:
> > Jens, you have a race in lo_clr_fd() (loop-6). I've put the fixed
> > variant on ftp.math.psu.edu/pub/viro/loop-S2.gz. Diff and you'll
> > see - it's in the very beginning of the lo_clr_fd().
> 
> Oops yeah you are right. Here's a diff of my current loop stuff
> against -ac4, Alan could you apply? Andrea suggested removing
> the loop private slab cache for buffer heads and just using the
> bh_cachep pool, and it seems like a good idea to me.

Erm... Jens, it really should be
	if (atomic_dec_and_test(...))
		up(...);
not just
	atomic_dec(...);
	up(...);

Otherwise you can end up with too early exit of loop_thread. Normally
it would not matter, but in pathological cases...