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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 52538C33CB7 for ; Fri, 31 Jan 2020 11:43:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F68E20705 for ; Fri, 31 Jan 2020 11:43:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580471014; bh=YUFEVwCNlddvIgP4Qt2+V8mNS/hMbmBZNY+3hypDBV0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=eG3NaIElxwuFx+0+cETHAA2hKVGcPfVQwqHQ2qUndSxJ+8m4APAAfAkgqH6d3Feq7 it0lq7aUxnyvgBBsqNj2trt68SZD583Ti1edplzBoXZckBoDrXSNAL+giAQBCkpZLn KC56w3haHo6dcko1gxnivySnwf5B/Z5cJql+vsKs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728487AbgAaLnd (ORCPT ); Fri, 31 Jan 2020 06:43:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:35872 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728400AbgAaLnd (ORCPT ); Fri, 31 Jan 2020 06:43:33 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 360FE206F0; Fri, 31 Jan 2020 11:43:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580471012; bh=YUFEVwCNlddvIgP4Qt2+V8mNS/hMbmBZNY+3hypDBV0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jW4AoN2X6dGPfIaw14g6qm7SO5ds6Xpe3ahdMQc74ts03Pw78P56dLgB+YVAAUZyE VROLZcQcq/SFvgav0mP3RRoXqxQ0in99t7On5kpNK/t553bMkNLc6BUEfImq9AxWiL sjpa5jnjYHH9utuJEy/wMS0VOlhqNy57JQxnTxpc= Date: Fri, 31 Jan 2020 11:43:27 +0000 From: Will Deacon To: Peter Zijlstra Cc: Greg Ungerer , Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] Rewrite Motorola MMU page-table layout Message-ID: <20200131114327.GB4298@willie-the-truck> References: <20200129103941.304769381@infradead.org> <8a81e075-d3bd-80c1-d869-9935fdd73162@linux-m68k.org> <20200131093813.GA3938@willie-the-truck> <20200131102239.GB14914@hirez.programming.kicks-ass.net> <20200131111459.GO14946@hirez.programming.kicks-ass.net> <20200131111824.GA4298@willie-the-truck> <20200131113139.GC14914@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200131113139.GC14914@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 31, 2020 at 12:31:39PM +0100, Peter Zijlstra wrote: > On Fri, Jan 31, 2020 at 11:18:24AM +0000, Will Deacon wrote: > > > > > +static inline pgtable_t pte_alloc_one(struct mm_struct *mm) > > > > > { > > > > > struct page *page = alloc_pages(GFP_DMA, 0); > > > > > pte_t *pte; > > > Does that mean we can drop the GFP_DMA too? If so, this all ends up > > looking very similar to the sun3 code wrt alloc/free and they could > > probably use the same implementation (since the generic code doesn't > > like out pgtable_t definition). > > Many software TLB archs have limits on what memory the TLB miss handler > itself can access (chicken-egg issues), it might be this is where the > GFP_DMA comes from. Fair enough, that sounds plausible. > I can't quickly find this in the CFV4e docs, but I'm not really reading > it carefully either. I can't find any code under arch/m68k/ which suggests it, but for now I guess we should stick with the old pgtable_t definition for sun3 with a comment (and keep the GFP_DMA in for coldfire). Will