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[216.228.121.143]) by mx.google.com with ESMTPS id m2si12932919ybp.153.2019.07.19.14.05.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 14:05:25 -0700 (PDT) Received-SPF: pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.143 as permitted sender) client-ip=216.228.121.143; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=RBMHQkFT; spf=pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.143 as permitted sender) smtp.mailfrom=jhubbard@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com 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== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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