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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 Cc: Mike Kravetz , Hugh Dickins , Peter Xu , Jason Gunthorpe , Gerd Hoffmann , Dongwon Kim , Junxiao Chang 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-Rspamd-Queue-Id: BD1B220073 X-Rspam-User: X-Stat-Signature: soqudxh8b3yy6bf6qn8kyieqchrisukt X-Rspamd-Server: rspam01 X-HE-Tag: 1689703401-158356 X-HE-Meta: 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 A2RsoPkz mjji5QJCD3DIQEnLwPDtN+yqcd1Wsk1L/s91af9akJQo8BBK4L1Hc64mT//LDTpDbD78YqqTQqogN0vYIn+lBlygbuJQHYpZPxrZWJgMlQHm7f8RgF/KbxFcAoLj2x6YWm4dSv5NHdHBDL+nV9mxVH+QfJefgmGdBq++BMqnY1PbsnB3A1oa2/TArxAlpPcBiAqaYQCC+27/ntnhgW9PPTyg6yRmLipYavWm5blh3iZtihVvq24IE5uRxxhsD+XAD1CKS05Sb5EjJWymCPbCASCFXYiCAd5/QXfYcpQVUR/US1WWzD+3aTjjp2/qHHUWMUmrmFtXkPqNoIT9v/CF0/rZff7OiNCsIrjbclsxBzNYh1aX98BYJzZAmcw/Qhom621T7Tr5SePCcL2Zs/YpwvBq6LM/ItNTV3DXtD5XFkr+dFIVnva1uib9eKGY3YzC2gDVlMFohvloMr6U= 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 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