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=-3.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=unavailable 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 7AE0DC43387 for ; Wed, 16 Jan 2019 13:18:34 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4866320859 for ; Wed, 16 Jan 2019 13:18:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="s1Cqso+W" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4866320859 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=k7lQct8qg2csTGSAAMRD45afNC5TNfIf6hvW1/Tj9Ww=; b=s1Cqso+WO4Kmwb UllaObqXIkwgDUdxHdwATgrUrcoX3DcvL8CBEbnEpm7memVOG18dv3Yjcnh+7aX/MvGy/yiorKM2e 7JsJva3jyXnlp4+kQBWcFVoVgcRE6Bobx6oPczkTpNDyti0oAjpOwAoFmq/zuGQk64yw2UxUANpUc bI8yShjrTBUJyHf+7JRSBd+fgfwT+tYrs4d4bu+Kz4yjIOv4WFMpRl4zYVwKki60ObXMy262CtfYW gk7zgaJZyYu7eHymfgfqMeuZIRIreTQlzy4FjkXPUNUbvyi3M3bz7kS2nOI5UfAkfm5burXrbdEdO FFKkQHMFfXsACDqBQL3Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gjl5T-0006WD-8z; Wed, 16 Jan 2019 13:18:31 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gjl5P-0006Vx-9a; Wed, 16 Jan 2019 13:18:27 +0000 Date: Wed, 16 Jan 2019 05:18:27 -0800 From: Matthew Wilcox To: Anshuman Khandual Subject: Re: [PATCH V2] mm: Introduce GFP_PGTABLE Message-ID: <20190116131827.GH6310@bombadil.infradead.org> References: <1547619692-7946-1-git-send-email-anshuman.khandual@arm.com> <20190116065703.GE24149@dhcp22.suse.cz> <20190116123018.GF6310@bombadil.infradead.org> <07d6a264-dccd-78ab-e8a9-2410bbef7b97@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <07d6a264-dccd-78ab-e8a9-2410bbef7b97@arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.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, linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu, mpe@ellerman.id.au, linux@armlinux.org.uk, mingo@redhat.com, vbabka@suse.cz, rientjes@google.com, palmer@sifive.com, greentime@andestech.com, marc.zyngier@arm.com, rppt@linux.vnet.ibm.com, shakeelb@google.com, kirill@shutemov.name, tglx@linutronix.de, Michal Hocko , 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 16, 2019 at 06:42:22PM +0530, Anshuman Khandual wrote: > On 01/16/2019 06:00 PM, Matthew Wilcox wrote: > > On Wed, Jan 16, 2019 at 07:57:03AM +0100, Michal Hocko wrote: > >> On Wed 16-01-19 11:51:32, Anshuman Khandual wrote: > >>> All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL | > >>> __GFP_ZERO) and using it for allocating page table pages. This causes some > >>> code duplication which can be easily avoided. GFP_KERNEL allocated and > >>> cleared out pages (__GFP_ZERO) are required for page tables on any given > >>> architecture. This creates a new generic GFP flag flag which can be used > >>> for any page table page allocation. Does not cause any functional change. > >>> > >>> GFP_PGTABLE is being added into include/asm-generic/pgtable.h which is the > >>> generic page tabe header just to prevent it's potential misuse as a general > >>> allocation flag if included in include/linux/gfp.h. > >> > >> I haven't reviewed the patch yet but I am wondering whether this is > >> really worth it without going all the way down to unify the common code > >> and remove much more code duplication. Or is this not possible for some > >> reason? > > > > Exactly what I suggested doing in response to v1. > > > > Also, the approach taken here is crazy. x86 has a feature that no other > > architecture has bothered to implement yet -- accounting page tables > > to the process. Yet instead of spreading that goodness to all other > > architectures, Anshuman has gone to more effort to avoid doing that. > > The basic objective for this patch is to create a common minimum allocation > flag that can be used by architectures but that still allows archs to add > on additional constraints if they see fit. This patch does not intend to > change functionality for any arch. I disagree with your objective. Making more code common is a great idea, but this patch is too unambitious. We should be heading towards one or two page table allocation functions instead of having every architecture do its own thing. So start there. Move the x86 function into common code and convert one other architecture to use it too. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel