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bh=60km6xH0HSvahM5c30+DJ4g8BodPX7+0LmwNaM0K8BI=; b=ExYwdc+DkS+fkDeydObiKNmENV tHOCg7o9tz01AsRah8P/Sr/9fh7XNjnnO8jUpwDGiiOtI4fzZuc6CUz0kowPjTXWC6ng/SIFsgqYN EJHOk3xQTOWZhterUYWYUuqnSOJrTgIRuwbsS0EX7HcK+HPf6oJYHWV5Bct4py7lGeNLo3+V3BDQD y5yp6ooOKpOsyzsFqaAIcs+xYoIbgqvVKxiXPkS/46cCAeQ19J2mBvZiqs9XbCzRkYaVcg210o8Hy kosgowf22Fkc7d716zpVdUVQa11HzeqnKB3bS3yoy0lNdGfuHQmF/UGjLKyQSo4URkuNgC0n1iHYd T4gVkX0w==; Received: from s01060023bee90a7d.cg.shawcable.net ([24.64.145.4] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kbEJI-00029J-SL; Fri, 06 Nov 2020 19:50:37 -0700 To: Jason Gunthorpe References: <20201106172206.GS36674@ziepe.ca> <20201106174223.GU36674@ziepe.ca> <2c2d2815-165e-2ef9-60d6-3ace7ff3aaa5@deltatee.com> <20201106180922.GV36674@ziepe.ca> <09885400-36f8-bc1d-27f0-a8adcf6104d4@deltatee.com> <20201106193024.GW36674@ziepe.ca> <03032637-0826-da76-aec2-121902b1c166@deltatee.com> <20201106195341.GA244516@ziepe.ca> <20201107001457.GB244516@ziepe.ca> From: Logan Gunthorpe Message-ID: <6f202b79-fa90-7cda-9ac9-457aa451530f@deltatee.com> Date: Fri, 6 Nov 2020 19:50:32 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201107001457.GB244516@ziepe.ca> Content-Language: en-US X-SA-Exim-Connect-IP: 24.64.145.4 X-SA-Exim-Rcpt-To: daniel.vetter@ffwll.ch, willy@infradead.org, ddutile@redhat.com, jhubbard@nvidia.com, iweiny@intel.com, christian.koenig@amd.com, dan.j.williams@intel.com, hch@lst.de, sbates@raithlin.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, jgg@ziepe.ca X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC PATCH 14/15] PCI/P2PDMA: Introduce pci_mmap_p2pmem() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Cc: =?UTF-8?Q?Christian_K=c3=b6nig?= , linux-pci@vger.kernel.org, Daniel Vetter , Ira Weiny , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Matthew Wilcox , John Hubbard , Dan Williams , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2020-11-06 5:14 p.m., Jason Gunthorpe wrote: > On Fri, Nov 06, 2020 at 01:03:26PM -0700, Logan Gunthorpe wrote: >> I don't think a function like that will work for the p2pmem use case. In >> order to implement proper page freeing I expect I'll need a loop around >> the allocator and vm_insert_mixed()... Something roughly like: >> >> for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { >> vaddr = pci_alloc_p2pmem(pdev, PAGE_SIZE); >> ret = vmf_insert_mixed(vma, addr, >> __pfn_to_pfn_t(virt_to_pfn(vaddr), PFN_DEV | PFN_MAP)); >> } >> >> That way we can call pci_free_p2pmem() when a page's ref count goes to >> zero. I suspect your use case will need to do something similar. > > Yes, but I would say the pci_alloc_p2pmem() layer should be able to > free pages on a page-by-page basis so you don't have to do stuff like > the above. > > There is often a lot of value in having physical contiguous addresses, > so allocating page by page as well seems poor. Agreed. But I'll have to dig to see if genalloc supports freeing blocks in different sizes than the allocations. Logan _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu