From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9BD4C433FE for ; Wed, 19 Oct 2022 14:53:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231661AbiJSOxt (ORCPT ); Wed, 19 Oct 2022 10:53:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230183AbiJSOxD (ORCPT ); Wed, 19 Oct 2022 10:53:03 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E02782875 for ; Wed, 19 Oct 2022 07:44:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=5mYsxjFeGKpcm5KRoXtnujxHXSvElTxW7YBXE+XahDo=; b=GYpzJ4IZIEfobfw2od09Tue2PV 4elW8HRHpOe79w1JijJ0TPTMFxGt3XDEFxytqo1o4IEXBn0Jl6GG1UAN5ndNpIdibD+jcICdO8hi1 itO01Z3AXa1DzUKuW6CQUdmH0SvB+9jnoZL3lqzkbXW3+VJGaXLkPzaEw0o7KN8qJdm2NzTHuBhfS BYnmWChb87rwU/Hn2dZilJdNHidtz4w9EcQudXpnm+nxGNe+/QS4TVsuFq9LRSfdlzyzO5mY/ExNK wcmVKKRtjnBBWonp0yslD/t5D6O0ynqDxw0n05xcJkhUpvATyFzFnczZmeY/95wkr6ilgN9jh8VqL 13yPXzsg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:34806) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1olAJL-0005qQ-Aa; Wed, 19 Oct 2022 15:44:47 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1olAJH-0002Ea-5V; Wed, 19 Oct 2022 15:44:43 +0100 Date: Wed, 19 Oct 2022 15:44:43 +0100 From: "Russell King (Oracle)" To: Giulio Benetti Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Anshuman Khandual , Andrew Morton , Kefeng Wang , Arnd Bergmann , Will Deacon Subject: Re: [PATCH v2 2/2] ARM: mm: convert empty_zero_page to array for consistency Message-ID: References: <20221018222503.90118-1-giulio.benetti@benettiengineering.com> <20221018222503.90118-2-giulio.benetti@benettiengineering.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221018222503.90118-2-giulio.benetti@benettiengineering.com> Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 19, 2022 at 12:25:03AM +0200, Giulio Benetti wrote: > ARM architecture is the only one to have empty_zero_page to be a > struct page pointer, while in all other implementations empty_zero_page is > a data pointer or directly an array(the zero page itself). So let's convert > empty_zero_page to an array for consistency and to avoid an early > allocation+dcache flush. Being the array in .bss it will be cleared earlier > in a more linear way(and a bit faster) way. > > Suggested-by: Arnd Bergmann > Signed-off-by: Giulio Benetti I'm completely against this approach. It introduces inefficiencies in paths we don't need, and also means that the zero page is at a fixed location relative to the kernel, neither of which I like in the slightest. Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!