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udmabuf: use vmf_insert_pfn and VM_PFNMAP for handling mmap
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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 *).

Link: https://lkml.kernel.org/r/20240624063952.1572359-6-vivek.kasireddy@intel.com
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Cc: Junxiao Chang <junxiao.chang@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Vivek Kasireddy authored and Andrew Morton committed Jul 12, 2024
1 parent 725553d commit 7d79cd7
Showing 1 changed file with 5 additions and 3 deletions.
8 changes: 5 additions & 3 deletions drivers/dma-buf/udmabuf.c
Original file line number Diff line number Diff line change
Expand Up @@ -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 = {
Expand All @@ -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;
}

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