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[23.128.96.18]) by mx.google.com with ESMTP id g13si4496141pji.109.2021.04.15.15.24.50; Thu, 15 Apr 2021 15:25:02 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=G7souXSd; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235279AbhDOWXK (ORCPT + 99 others); Thu, 15 Apr 2021 18:23:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237420AbhDOWXD (ORCPT ); Thu, 15 Apr 2021 18:23:03 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A8F4C061763; Thu, 15 Apr 2021 15:22:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=yCQQJkhIcMUmiG+jHzQ5AkwvKN7ARCVTOi/VwlhPfFg=; b=G7souXSd1HEpHpbqWUh5lxEnqG 72yPOet6m6dISSd7axpLwF1GuIay1RV/45F6tKEj6BDbJeHO2gR22kOlntma0FZZPbcvmmD/MXrGS ZotJA+5b3Jkfa2AaHAwGam44BVigQtO2OUUWx5K1MxtG1pZ5CiucXxAz7iHzXIdBtZHCcO6t1Akn0 Jf6e7BP75Cnv6p6VHUjizlw9iKFlwP1TXfBnuT7H8BBwGli/+jYj8lop4Y87z4ime9iPQZllplUcx wCGblTZ9lVpuPqcW+hkdOWg1I0lN04CeqlSLB7/d6d7euI/yXPCIGsLBBIFSox+o2XhR8MFrZidLv V60jL89w==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lXANH-0099VJ-Ux; Thu, 15 Apr 2021 22:22:19 +0000 Date: Thu, 15 Apr 2021 23:22:11 +0100 From: Matthew Wilcox To: David Laight Cc: Jesper Dangaard Brouer , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "netdev@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mips@vger.kernel.org" , Ilias Apalodimas , Matteo Croce , Grygorii Strashko , Arnd Bergmann , Christoph Hellwig Subject: Re: [PATCH 1/1] mm: Fix struct page layout on 32-bit systems Message-ID: <20210415222211.GG2531743@casper.infradead.org> References: <20210411103318.GC2531743@casper.infradead.org> <20210412011532.GG2531743@casper.infradead.org> <20210414101044.19da09df@carbon> <20210414115052.GS2531743@casper.infradead.org> <20210414211322.3799afd4@carbon> <20210414213556.GY2531743@casper.infradead.org> <20210415200832.32796445@carbon> <20210415182155.GD2531743@casper.infradead.org> <5179a01a462f43d6951a65de2a299070@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5179a01a462f43d6951a65de2a299070@AcuMS.aculab.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 15, 2021 at 09:11:56PM +0000, David Laight wrote: > Isn't it possible to move the field down one long? > This might require an explicit zero - but this is not a common > code path - the extra write will be noise. Then it overlaps page->mapping. See emails passim.