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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 5BBAFC10F29 for ; Tue, 17 Mar 2020 13:50:12 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 3CA7020757 for ; Tue, 17 Mar 2020 13:50:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3CA7020757 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=amd-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AC3A16E13D; Tue, 17 Mar 2020 13:50:08 +0000 (UTC) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9639D6E0E8; Tue, 17 Mar 2020 12:28:17 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 1763568BFE; Tue, 17 Mar 2020 13:28:14 +0100 (CET) Date: Tue, 17 Mar 2020 13:28:13 +0100 From: Christoph Hellwig To: Jason Gunthorpe Subject: Re: [PATCH 3/4] mm: simplify device private page handling in hmm_range_fault Message-ID: <20200317122813.GA11866@lst.de> References: <20200316193216.920734-1-hch@lst.de> <20200316193216.920734-4-hch@lst.de> <7256f88d-809e-4aba-3c46-a223bd8cc521@nvidia.com> <20200317121536.GQ20941@ziepe.ca> <20200317122445.GA11662@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200317122445.GA11662@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-Mailman-Approved-At: Tue, 17 Mar 2020 13:50:08 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ralph Campbell , amd-gfx@lists.freedesktop.org, nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kvm-ppc@vger.kernel.org, Christoph Hellwig , linux-mm@kvack.org, Jerome Glisse , Ben Skeggs , Dan Williams , Bharata B Rao , Christian =?iso-8859-1?Q?K=F6nig?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On Tue, Mar 17, 2020 at 01:24:45PM +0100, Christoph Hellwig wrote: > On Tue, Mar 17, 2020 at 09:15:36AM -0300, Jason Gunthorpe wrote: > > > Getting rid of HMM_PFN_DEVICE_PRIVATE seems reasonable to me since a driver can > > > look at the struct page but what if a driver needs to fault in a page from > > > another device's private memory? Should it call handle_mm_fault()? > > > > Isn't that what this series basically does? > > > > The dev_private_owner is set to the type of pgmap the device knows how > > to handle, and everything else is automatically faulted for the > > device. > > > > If the device does not know how to handle device_private then it sets > > dev_private_owner to NULL and it never gets device_private pfns. > > > > Since the device_private pfn cannot be dma mapped, drivers must have > > explicit support for them. > > No, with this series (and all actual callers before this series) > we never fault in device private pages. IFF we want to fault it in we'd need something like this. But I'd really prefer to see test cases for that first. diff --git a/mm/hmm.c b/mm/hmm.c index b75b3750e03d..2884a3d11a1f 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -276,7 +276,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, if (!fault && !write_fault) return 0; - if (!non_swap_entry(entry)) + if (!non_swap_entry(entry) || is_device_private_entry(entry)) goto fault; if (is_migration_entry(entry)) { _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx