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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 00231C4363A for ; Tue, 27 Oct 2020 08:08:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97333207C3 for ; Tue, 27 Oct 2020 08:08:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dRm7AtSG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731037AbgJ0IIV (ORCPT ); Tue, 27 Oct 2020 04:08:21 -0400 Received: from casper.infradead.org ([90.155.50.34]:34146 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729449AbgJ0IIV (ORCPT ); Tue, 27 Oct 2020 04:08:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=4pKuAsyiH24Ww755Jm+xfRiXHhuYbUQ5IacY5+bzdvs=; b=dRm7AtSGKZKfRHsJEG25DPDGe7 vVZJ8ERkUFGMp09BUle110ztL+kZg9+nmbxc/Lpq107XF43uEG7oQtWE/v6YMtSXHuzNMSVzTNmHk 8oOQPKa1yhgWUhhsPmYqnAIkLCBdFafBtwIrIsYu8i+l+PXp4vhs1vHS06QE5Kaymq9sQCDG4duQB hgTLWQr3FB6A37H0aajYEY0j9UVQiHTbWmI6YDXvfVVzczNm0pD+XoINbDP6VGrEegf+kvpecz5dK ohxHmbwa7yDMbZl36e1MqWbk5c0h4yWamrtTYtY+qdvc1tKaPP8aiUEIKws+tnXFl/iZ6aIBnqY+w T1iaLjrA==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kXK1g-0000hv-Ld; Tue, 27 Oct 2020 08:08:16 +0000 Date: Tue, 27 Oct 2020 08:08:16 +0000 From: Christoph Hellwig To: Jason Gunthorpe Cc: Christoph Hellwig , Daniel Vetter , Jianxin Xiong , linux-rdma@vger.kernel.org, dri-devel@lists.freedesktop.org, Leon Romanovsky , Doug Ledford , Daniel Vetter , Christian Koenig Subject: Re: [PATCH v6 1/4] RDMA/umem: Support importing dma-buf as user memory region Message-ID: <20201027080816.GA2692@infradead.org> References: <1603471201-32588-1-git-send-email-jianxin.xiong@intel.com> <1603471201-32588-2-git-send-email-jianxin.xiong@intel.com> <20201023164911.GF401619@phenom.ffwll.local> <20201023182005.GP36674@ziepe.ca> <20201024074807.GA3112@infradead.org> <20201026122637.GQ36674@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201026122637.GQ36674@ziepe.ca> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Mon, Oct 26, 2020 at 09:26:37AM -0300, Jason Gunthorpe wrote: > On Sat, Oct 24, 2020 at 08:48:07AM +0100, Christoph Hellwig wrote: > > On Fri, Oct 23, 2020 at 03:20:05PM -0300, Jason Gunthorpe wrote: > > > The problem is we have RDMA drivers that assume SGL's have a valid > > > struct page, and these hacky/wrong P2P sgls that DMABUF creates cannot > > > be passed into those drivers. > > > > RDMA drivers do not assume scatterlist have a valid struct page, > > scatterlists are defined to have a valid struct page. Any scatterlist > > without a struct page is completely buggy. > > It is not just having the struct page, it needs to be a CPU accessible > one for memcpy/etc. They aren't correct with the > MEMORY_DEVICE_PCI_P2PDMA SGLs either. Exactly.