From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 1A2426B000D for ; Thu, 1 Mar 2018 09:51:01 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id q2so2713431pgn.22 for ; Thu, 01 Mar 2018 06:51:01 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id i11si3113929pfi.388.2018.03.01.06.51.00 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 01 Mar 2018 06:51:00 -0800 (PST) Date: Thu, 1 Mar 2018 06:50:58 -0800 From: Matthew Wilcox Subject: Re: [PATCH v3 0/4] Split page_type out from mapcount Message-ID: <20180301145058.GA19662@bombadil.infradead.org> References: <20180228223157.9281-1-willy@infradead.org> <20180301081750.42b135c3@mschwideX1> <20180301124412.gm6jxwzyfskzxspa@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180301124412.gm6jxwzyfskzxspa@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Martin Schwidefsky , linux-mm@kvack.org, Matthew Wilcox , linux-kernel@vger.kernel.org On Thu, Mar 01, 2018 at 03:44:12PM +0300, Kirill A. Shutemov wrote: > On Thu, Mar 01, 2018 at 08:17:50AM +0100, Martin Schwidefsky wrote: > > Yeah, that is a nasty bit of code. On s390 we have 2K page tables (pte) > > but 4K pages. If we use full pages for the pte tables we waste 2K of > > memory for each of the tables. So we allocate 4K and split it into two > > 2K pieces. Now we have to keep track of the pieces to be able to free > > them again. > > Have you considered to use slab for page table allocation instead? > IIRC some architectures practice this already. You're not allowed to do that any more. Look at pgtable_page_ctor(), or rather ptlock_init(). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org