From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755986Ab1KHW5J (ORCPT ); Tue, 8 Nov 2011 17:57:09 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:46768 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753353Ab1KHW5I (ORCPT ); Tue, 8 Nov 2011 17:57:08 -0500 Date: Tue, 8 Nov 2011 14:57:06 -0800 From: Andrew Morton To: Jacobo Giralt Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, mgorman@suse.de, minchan.kim@gmail.com, hughd@google.com, hannes@cmpxchg.org, Nick Piggin Subject: Re: [PATCH] mm: migrate: One less atomic operation Message-Id: <20111108145706.11da104e.akpm@linux-foundation.org> In-Reply-To: <1320503897.2428.8.camel@discretia> References: <1320503897.2428.8.camel@discretia> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 05 Nov 2011 15:38:17 +0100 Jacobo Giralt wrote: > >From 3754c8617ef4377ce2ca2e3b28bdc28f8de1aa0d Mon Sep 17 00:00:00 2001 > From: Jacobo Giralt > Date: Sat, 5 Nov 2011 13:12:50 +0100 > Subject: [PATCH] mm: migrate: One less atomic operation > > migrate_page_move_mapping drops a reference from the > old page after unfreezing its counter. Both operations > can be merged into a single atomic operation by > directly unfreezing to one less reference. > > The same applies to migrate_huge_page_move_mapping. > Fair enough. urgh, you made me look at stuff :( page_unfreeze_refs() and set_page_refcounted() are fishily similar. page_unfreeze_refs() should use set_page_count(). set_page_count() is defined in the wrong file. set_page_refcounted() should use page_count(). iow, a bit of a mess.