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Date: Tue, 8 May 2007 21:08:09 +0100 (BST)
From: Hugh Dickins <hugh@veritas.com>
Subject: Re: [rfc] optimise unlock_page
In-Reply-To: <20070508114003.GB19294@wotan.suse.de>
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To: Nick Piggin <npiggin@suse.de>
Cc: linux-arch@vger.kernel.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Andrew Morton <akpm@linux-foundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Linux Memory Management List <linux-mm@kvack.org>
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On Tue, 8 May 2007, Nick Piggin wrote:

> This patch trades a page flag for a significant improvement in the unlock_page
> fastpath. Various problems in the previous version were spotted by Hugh and
> Ben (and fixed in this one).
> 
> Comments?

Seems there's still a bug there.  I get hangs on the page lock, on
i386 and on x86_64 and on powerpc: sometimes they unhang themselves
after a while (presume other activity does the wakeup).  Obvious even
while booting (Starting udevd).  Sorry, not had time to investigate.

Hugh