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Tue, 13 Aug 2019 00:09:04 +0000 (UTC) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 12 Aug 2019 17:09:05 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 12 Aug 2019 17:09:03 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 12 Aug 2019 17:09:03 -0700 Received: from [10.2.165.207] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 13 Aug 2019 00:09:02 +0000 Subject: Re: [RFC PATCH 2/2] mm/gup: introduce vaddr_pin_pages_remote() To: Ira Weiny CC: Andrew Morton , Christoph Hellwig , Dan Williams , Dave Chinner , Jan Kara , Jason Gunthorpe , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , LKML , , , References: <20190812015044.26176-1-jhubbard@nvidia.com> <20190812015044.26176-3-jhubbard@nvidia.com> <20190812234950.GA6455@iweiny-DESK2.sc.intel.com> X-Nvconfidentiality: public From: John Hubbard Message-ID: <38d2ff2f-4a69-e8bd-8f7c-41f1dbd80fae@nvidia.com> Date: Mon, 12 Aug 2019 17:07:32 -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: <20190812234950.GA6455@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"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1565654945; bh=/wUWIK2KCWN+EdOxtD3Lx3ieNzAYWw6oiQTfkMzs1z4=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=fabDrYOKwUNPuchzbriK5AMZnZocxegfpaGb1YYxCqXZ4wtcHIpx96Odw5k4ICzzT iZpl3veS/CAV9dLRwYMRBkNIHfdxLkUfpXyqIoX7MnrHx9s6pT4udv1r1a/a5c/3h5 tZHPEp/ZLWCUEqqdJKpiANdAJLbkVzkBAV3TndttzDMnleK2AIW2H4b2DkINQlezTT BY2P2+pn0RTBJfIR0Wmogyu9RLO4dLaugR7l4KAw9fjioVlORt5yAHDM2QgWHJyzK5 1JQeOscC3TwaeYqzJdN7IzLWb1tfFJadyhCYQA7OwMUGp3YXh4J32EZuea9IBQ1jgA GWeSN2C/h30cw== 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 8/12/19 4:49 PM, Ira Weiny wrote: > On Sun, Aug 11, 2019 at 06:50:44PM -0700, john.hubbard@gmail.com wrote: >> From: John Hubbard ... >> diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c >> index 53085896d718..fdff034a8a30 100644 >> --- a/drivers/infiniband/core/umem_odp.c >> +++ b/drivers/infiniband/core/umem_odp.c >> @@ -534,7 +534,7 @@ static int ib_umem_odp_map_dma_single_page( >> } >> >> out: >> - put_user_page(page); >> + vaddr_unpin_pages(&page, 1, &umem_odp->umem.vaddr_pin); >> >> if (remove_existing_mapping) { >> ib_umem_notifier_start_account(umem_odp); >> @@ -635,9 +635,10 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt, >> * complex (and doesn't gain us much performance in most use >> * cases). >> */ >> - npages = get_user_pages_remote(owning_process, owning_mm, >> + npages = vaddr_pin_pages_remote(owning_process, owning_mm, >> user_virt, gup_num_pages, >> - flags, local_page_list, NULL, NULL); >> + flags, local_page_list, NULL, NULL, >> + &umem_odp->umem.vaddr_pin); > > Thinking about this part of the patch... is this pin really necessary? This > code is not doing a long term pin. The page just needs a reference while we > map it into the devices page tables. Once that is done we should get notifiers > if anything changes and we can adjust. right? > OK, now it's a little interesting: the FOLL_PIN is necessary, but maybe not FOLL_LONGTERM. Illustrating once again that it's actually necessary to allow these flags to vary independently. And that leads to another API refinement idea: let's set FOLL_PIN within the vaddr_pin_pages*() wrappers, and set FOLL_LONGTER in the *callers* of those wrappers, yes? thanks, -- John Hubbard NVIDIA