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Date: Wed, 7 May 2008 13:56:23 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrea Arcangeli <andrea@qumranet.com>
cc: Andrew Morton <akpm@linux-foundation.org>,
       Christoph Lameter <clameter@sgi.com>, Jack Steiner <steiner@sgi.com>,
       Robin Holt <holt@sgi.com>, Nick Piggin <npiggin@suse.de>,
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       Marcelo Tosatti <marcelo@kvack.org>, Eric Dumazet <dada1@cosmosbay.com>,
       "Paul E. McKenney" <paulmck@us.ibm.com>
Subject: Re: [PATCH 08 of 11] anon-vma-rwsem
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On Wed, 7 May 2008, Andrea Arcangeli wrote:
> 
> Convert the anon_vma spinlock to a rw semaphore. This allows concurrent
> traversal of reverse maps for try_to_unmap() and page_mkclean(). It also
> allows the calling of sleeping functions from reverse map traversal as
> needed for the notifier callbacks. It includes possible concurrency.

This also looks very debatable indeed. The only performance numbers quoted 
are:

>   This results in f.e. the Aim9 brk performance test to got down by 10-15%.

which just seems like a total disaster.

The whole series looks bad, in fact. Lack of authorship, bad single-line 
description, and the code itself sucks so badly that it's not even funny.

NAK NAK NAK. All of it. It stinks.

		Linus