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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,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 8AE5FC48BD4 for ; Tue, 25 Jun 2019 07:47:10 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 EC28320659 for ; Tue, 25 Jun 2019 07:47:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC28320659 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45Xyt34BcyzDqFC for ; Tue, 25 Jun 2019 17:47:07 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=newverein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 45Xyq04S5zzDqJK for ; Tue, 25 Jun 2019 17:44:28 +1000 (AEST) Received: by newverein.lst.de (Postfix, from userid 2407) id 5891C68B02; Tue, 25 Jun 2019 09:43:54 +0200 (CEST) Date: Tue, 25 Jun 2019 09:43:53 +0200 From: Christoph Hellwig To: Jason Gunthorpe Subject: Re: [PATCH 01/16] mm: use untagged_addr() for get_user_pages_fast addresses Message-ID: <20190625074353.GC30815@lst.de> References: <20190611144102.8848-1-hch@lst.de> <20190611144102.8848-2-hch@lst.de> <20190621133911.GL19891@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190621133911.GL19891@ziepe.ca> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: x86@kernel.org, Rich Felker , Yoshinori Sato , linux-sh@vger.kernel.org, James Hogan , linuxppc-dev@lists.ozlabs.org, Khalid Aziz , Nicholas Piggin , "David S. Miller" , linux-mm@kvack.org, Paul Burton , Paul Mackerras , Andrey Konovalov , sparclinux@vger.kernel.org, linux-mips@vger.kernel.org, Linus Torvalds , Christoph Hellwig , linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Jun 21, 2019 at 10:39:11AM -0300, Jason Gunthorpe wrote: > Hmm, this function, and the other, goes on to do: > > if (unlikely(!access_ok((void __user *)start, len))) > return 0; > > and I thought that access_ok takes in the tagged pointer? > > How about re-order it a bit? Actually.. I we reorder this we'd need to to duplicate a few things due to the zero/negative length checking. Given the feedback from Khalid I'd thus rather skip the reorder for now. If we have a good reason we could add it back, but it would be a bit involved.