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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED1C5C43612 for ; Mon, 14 Jan 2019 04:28:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C622D206B7 for ; Mon, 14 Jan 2019 04:28:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726516AbfANE2X (ORCPT ); Sun, 13 Jan 2019 23:28:23 -0500 Received: from foss.arm.com ([217.140.101.70]:54520 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfANE2W (ORCPT ); Sun, 13 Jan 2019 23:28:22 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 628C180D; Sun, 13 Jan 2019 20:28:22 -0800 (PST) Received: from [10.162.42.129] (p8cg001049571a15.blr.arm.com [10.162.42.129]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D48C03F5BD; Sun, 13 Jan 2019 20:28:13 -0800 (PST) Subject: Re: [PATCH] mm: Introduce GFP_PGTABLE To: Matthew Wilcox , Christophe Leroy Cc: mark.rutland@arm.com, mhocko@suse.com, linux-sh@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.cs.columbia.edu, linux@armlinux.org.uk, mingo@redhat.com, vbabka@suse.cz, rientjes@google.com, marc.zyngier@arm.com, rppt@linux.vnet.ibm.com, shakeelb@google.com, kirill@shutemov.name, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, ard.biesheuvel@linaro.org, robin.murphy@arm.com, steve.capper@arm.com, christoffer.dall@arm.com, james.morse@arm.com, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org References: <1547288798-10243-1-git-send-email-anshuman.khandual@arm.com> <20190112121230.GQ6310@bombadil.infradead.org> <20190112154944.GT6310@bombadil.infradead.org> From: Anshuman Khandual Message-ID: <48f81a76-2b2d-5060-d9bc-c42d5b5975c3@arm.com> Date: Mon, 14 Jan 2019 09:58:14 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190112154944.GT6310@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/12/2019 09:19 PM, Matthew Wilcox wrote: > On Sat, Jan 12, 2019 at 02:49:29PM +0100, Christophe Leroy wrote: >> As far as I can see, >> >> #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) >> >> So what's the difference between: >> >> (GFP_KERNEL_ACCOUNT | __GFP_ZERO) & ~__GFP_ACCOUNT >> >> and >> >> (GFP_KERNEL | __GFP_ZERO) & ~__GFP_ACCOUNT > > Nothing. But there's a huge difference in the other parts of that same > file where GFP_ACCOUNT is _not_ used. > > I think this unification is too small to bother with. Something I've > had on my todo list for some time and have not done anything about > is to actually unify all of the architecture pte/pmd/... allocations. > There are tricks some architectures use that others would benefit from. Sure. Could you please elaborate on this ? Invariably all kernel pgtable page allocations should use GFP_PGTABLE and all user page table allocation should use (GFP_PGTABLE | __GFP_ACCOUNT). Ideally there should be default generic functions user_pgtable_gfp() or kernel_pgtable_gfp() returning these values. Overrides can be provided if an arch still wants some more control.