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[2003:cb:c740:6200:84e1:eabc:8e2:7429]) by smtp.gmail.com with ESMTPSA id 9-20020a05600c228900b003fba92fad35sm10875616wmf.26.2023.07.18.11.03.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Jul 2023 11:03:16 -0700 (PDT) Message-ID: <05b60d58-80e2-730f-f8e1-e61fc5f25680@redhat.com> Date: Tue, 18 Jul 2023 20:03:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v2 1/2] udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap To: Vivek Kasireddy , dri-devel@lists.freedesktop.org, linux-mm@kvack.org References: <20230718082605.1570740-1-vivek.kasireddy@intel.com> <20230718082605.1570740-2-vivek.kasireddy@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230718082605.1570740-2-vivek.kasireddy@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dongwon Kim , Junxiao Chang , Hugh Dickins , Peter Xu , Gerd Hoffmann , Jason Gunthorpe , Mike Kravetz Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 18.07.23 10:26, Vivek Kasireddy wrote: > Add VM_PFNMAP to vm_flags in the mmap handler to ensure that > the mappings would be managed without using struct page. > > And, in the vm_fault handler, use vmf_insert_pfn to share the > page's pfn to userspace instead of directly sharing the page > (via struct page *). > > Cc: David Hildenbrand > Cc: Mike Kravetz > Cc: Hugh Dickins > Cc: Peter Xu > Cc: Jason Gunthorpe > Cc: Gerd Hoffmann > Cc: Dongwon Kim > Cc: Junxiao Chang > Suggested-by: David Hildenbrand > Signed-off-by: Vivek Kasireddy > --- > drivers/dma-buf/udmabuf.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c > index c40645999648..820c993c8659 100644 > --- a/drivers/dma-buf/udmabuf.c > +++ b/drivers/dma-buf/udmabuf.c > @@ -35,12 +35,13 @@ static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf) > struct vm_area_struct *vma = vmf->vma; > struct udmabuf *ubuf = vma->vm_private_data; > pgoff_t pgoff = vmf->pgoff; > + unsigned long pfn; > > if (pgoff >= ubuf->pagecount) > return VM_FAULT_SIGBUS; > - vmf->page = ubuf->pages[pgoff]; > - get_page(vmf->page); > - return 0; > + > + pfn = page_to_pfn(ubuf->pages[pgoff]); > + return vmf_insert_pfn(vma, vmf->address, pfn); > } > > static const struct vm_operations_struct udmabuf_vm_ops = { > @@ -56,6 +57,7 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) > > vma->vm_ops = &udmabuf_vm_ops; > vma->vm_private_data = ubuf; > + vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); > return 0; > } > Looks reasonable to me. Acked-by: David Hildenbrand -- Cheers, David / dhildenb