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Fri, 16 Oct 2020 07:54:29 +0000 (UTC) X-HE-Tag: book45_2e17e132721b X-Filterd-Recvd-Size: 4192 Received: from hqnvemgate25.nvidia.com (hqnvemgate25.nvidia.com [216.228.121.64]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 07:54:28 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Fri, 16 Oct 2020 00:53:43 -0700 Received: from [10.2.49.77] (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 16 Oct 2020 07:54:19 +0000 Subject: Re: [PATCH v2 05/17] mm/frame-vector: Use FOLL_LONGTERM To: Daniel Vetter , DRI Development , LKML CC: , , , , , , Daniel Vetter , Jason Gunthorpe , Pawel Osciak , Marek Szyprowski , "Kyungmin Park" , Tomasz Figa , "Mauro Carvalho Chehab" , Andrew Morton , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Dan Williams References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-6-daniel.vetter@ffwll.ch> From: John Hubbard Message-ID: <4685181e-8306-0d96-8be6-592b3c563cbf@nvidia.com> Date: Fri, 16 Oct 2020 00:54:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201009075934.3509076-6-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1602834823; bh=x8+KhcjN/0jeBmkHwcjBNjUK8qbDE0ZVZJYKZ9Z6VGs=; h=Subject:To:CC:References:From:Message-ID:Date:User-Agent: MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=OPXG7m+swcryyW3+1c3mxRCD9ELJ64r6RX1Dgjsv/DxKINT3TrWkfzRvFH5oOjwQ9 kbmWxE8cjt++1sfq9zZBm7pAsjxLHRKxIkJrIYBO5d5BHLfs1GBTG4uNWzgJwAYEib a0tpEVj2BXEbDUUj0WNA08KLGk0UpBLrh6Q4zl4oRKuwi2vFzQU7IWPvzl60U5doRa 9Sx7wqrwS1T6lY56FeeLMgq9fZLnJB5MNWWrmUCdHStngTzwSQOW6ZGYVnKoe93gas pNw8s4iejdBCZ9jkBUIDbZgPpbSPLosjj5nPK4785xOzYYi5NQgwhH2Nz6WyvBj4Gr OGagG2GGGM95w== 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 10/9/20 12:59 AM, Daniel Vetter wrote: ... > @@ -48,40 +47,25 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > > start = untagged_addr(start); > > - mmap_read_lock(mm); > - locked = 1; > - vma = find_vma_intersection(mm, start, start + 1); > - if (!vma) { > - ret = -EFAULT; > - goto out; > - } > - > - /* > - * While get_vaddr_frames() could be used for transient (kernel > - * controlled lifetime) pinning of memory pages all current > - * users establish long term (userspace controlled lifetime) > - * page pinning. Treat get_vaddr_frames() like > - * get_user_pages_longterm() and disallow it for filesystem-dax > - * mappings. > - */ > - if (vma_is_fsdax(vma)) { > - ret = -EOPNOTSUPP; > - goto out; > - } > - > - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { > + ret = pin_user_pages_fast(start, nr_frames, > + FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, > + (struct page **)(vec->ptrs)); > + if (ret > 0) { None of the callers that we have today will accept anything less than ret == nr_frames. And the whole partially pinned region idea turns out to be just not useful for almost everyone, from what I recall of the gup/pup call sites. So I wonder if we should just have get_vaddr_frames do the cleanup here and return -EFAULT, if ret != nr_frames ? thanks, -- John Hubbard NVIDIA