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Fri, 1 Nov 2019 10:53:45 +1100 (AEDT) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 31 Oct 2019 16:53:46 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 31 Oct 2019 16:53:40 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 31 Oct 2019 16:53:40 -0700 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 31 Oct 2019 23:53:39 +0000 Subject: Re: [PATCH 19/19] Documentation/vm: add pin_user_pages.rst To: Ira Weiny References: <20191030224930.3990755-1-jhubbard@nvidia.com> <20191030224930.3990755-20-jhubbard@nvidia.com> <20191031234922.GM14771@iweiny-DESK2.sc.intel.com> From: John Hubbard Message-ID: <85de5845-d403-dc31-4f3b-f006c4a7b2a2@nvidia.com> Date: Thu, 31 Oct 2019 16:53:39 -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: <20191031234922.GM14771@iweiny-DESK2.sc.intel.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) 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=1572566026; bh=vjWEFq7fNfPLFBVwJSkbaC93kNFVP4oSS83LfHWMvq4=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=huUn94OR5NVpnI/NdJ3vTkz0Aags6KkZKFci9Fz5nHWE/pFd85Cktt11D1CQUWnOi UTPR4qv0QPFgv/ONDQLcPNmALzbnAKqxnplv+MLSg0Lt5g7PakxG9E1PUBNwTzA4dg k5IpEf3tN9qoIDtETnu//UzIRidkW3Ptv7qB5nHQktouL6xNQxT4kKgi3v8i+IvKdv ffAJkGbaVSplOPwrv6cDHUyGv5RC9JGCEhmv/YdTyy6OAb8LAtR2JiVi7nJzrIOI/o Ji4iiKunwQFUjG8sIvZShB4w9wwsMfCPKf36InyfzANf6JSqnPhJXe3qBOy7AOjUTp IqJ2SDnd3CyHg== 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: Michal Hocko , Jan Kara , kvm@vger.kernel.org, linux-doc@vger.kernel.org, David Airlie , Dave Chinner , dri-devel@lists.freedesktop.org, LKML , linux-mm@kvack.org, Paul Mackerras , linux-kselftest@vger.kernel.org, Shuah Khan , Jonathan Corbet , linux-rdma@vger.kernel.org, Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , linux-media@vger.kernel.org, linux-block@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Al Viro , Dan Williams , Mauro Carvalho Chehab , bpf@vger.kernel.org, Magnus Karlsson , Jens Axboe , netdev@vger.kernel.org, Alex Williamson , Daniel Vetter , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S . Miller" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 10/31/19 4:49 PM, Ira Weiny wrote: > On Wed, Oct 30, 2019 at 03:49:30PM -0700, John Hubbard wrote: >> Document the new pin_user_pages() and related calls >> and behavior. >> >> Thanks to Jan Kara and Vlastimil Babka for explaining the 4 cases >> in this documentation. (I've reworded it and expanded on it slightly.) > > As I said before I think this may be better in a previous patch where you > reference it. Yes, I'll merge this in with patch #5 ("mm/gup: introduce pin_user_pages*() and FOLL_PIN"). ... >> +TODO: There is also a special case when the pages are DAX pages: in addition to >> +the above flags, the caller needs something like a layout lease on the >> +associated file. This is yet to be implemented. When it is implemented, it's >> +expected that the lease will be a prerequisite to setting FOLL_LONGTERM. > > For now we probably want to leave this note out until we figure out how this is > going to work. Best to say something like: > > Some pages, such as DAX pages, can't be pinned with longterm pins and will > fail. > OK, that is better, I'll use that instead of the "TODO". thanks, John Hubbard NVIDIA