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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 95F46C76195 for ; Fri, 19 Jul 2019 21:05:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69DA121873 for ; Fri, 19 Jul 2019 21:05:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="RBMHQkFT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388524AbfGSVF0 (ORCPT ); Fri, 19 Jul 2019 17:05:26 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:15868 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727972AbfGSVFZ (ORCPT ); Fri, 19 Jul 2019 17:05:25 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 19 Jul 2019 14:05:25 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Fri, 19 Jul 2019 14:05:24 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Fri, 19 Jul 2019 14:05:24 -0700 Received: from [10.110.48.28] (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 19 Jul 2019 21:05:24 +0000 Subject: Re: [PATCH v3] staging: kpc2000: Convert put_page to put_user_page*() To: Matt Sickler , Bharath Vedartham , "ira.weiny@intel.com" , "jglisse@redhat.com" , "gregkh@linuxfoundation.org" CC: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "devel@driverdev.osuosl.org" References: <20190719200235.GA16122@bharath12345-Inspiron-5559> From: John Hubbard X-Nvconfidentiality: public Message-ID: <3948879c-5764-4245-e950-eb4749aafe5b@nvidia.com> Date: Fri, 19 Jul 2019 14:05:23 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1563570325; bh=uXXZ8OaRelUTVBhhS709HcwBaF4jbMLR5EBDQ41vffw=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=RBMHQkFTRPQgCd7gP4P+7u6BJdhh2b31ep8178Yi5S3jKNIPqrnwL2KL1601Z+iuQ 9V44LCZdjYVWOPr8mb/RBqFqi+lWyoa4VLjFHCODAHQmfqss6YPvwRWYQ24WU7q3lW JEhvpFzEci71ms+nbfMOZqVZJIL7B2u3yJJhe+lnLiFchga6FTAWxwHtKCj2i1af+G tWD9LYiUxhJnZ6l0hzXLh3TFsed9xgGzTVtHb8LdrvqemTRFs0fukUMZ0VogQapToK fOZyAxJ+lOP22NjLrdU81USY8v73UiGyZDvqTYlE+oi5v9TNpmoafHVddNgLIgfFML fmlLIcQLM3yuQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/19/19 1:59 PM, Matt Sickler wrote: >> From: Bharath Vedartham >> Changes since v2 >> - Added back PageResevered check as suggested by John Hubbard. >> >> The PageReserved check needs a closer look and is not worth messing >> around with for now. >> >> Matt, Could you give any suggestions for testing this patch? > > Myself or someone else from Daktronics would have to do the testing since the > hardware isn't really commercially available. I've been toying with the idea > of asking for a volunteer from the mailing list to help me out with this - I'd > send them some hardware and they'd do all the development and testing. :) > I still have to run that idea by Management though. > >> If in-case, you are willing to pick this up to test. Could you >> apply this patch to this tree and test it with your devices? > > I've been meaning to get to testing the changes to the drivers since upstreaming > them, but I've been swamped with other development. I'm keeping an eye on the > mailing lists, so I'm at least aware of what is coming down the pipe. > I'm not too worried about this specific change, even though I don't really know > if the reserved check and the dirtying are even necessary. > It sounded like John's suggestion was to not do the PageReserved() check and just > use put_user_pges_dirty() all the time. John, is that incorrect? > That's what I suggested at first. But then I saw at least one other place where this pattern is being used, and it shook my confidence. I don't clearly see what the PageReserved check is protecting against here, but it's better to be safe, and do things in two steps: step 1 is *only* convert from put_page() to put_user_page(), and step 2 is to maybe remove the PageReserved() check, once fully understood. thanks, -- John Hubbard NVIDIA