[PATCH v2 0/2] udmabuf: Add back support for mapping hugetlb pages (v2)

[Vivek Kasireddy <vivek.kasireddy@intel.com>]

The first patch ensures that the mappings needed for handling mmap
operation would be managed by using the pfn instead of struct page.
The second patch restores support for mapping hugetlb pages where
subpages of a hugepage are not directly used anymore (main reason
for revert) and instead the hugetlb pages and the relevant offsets
are used to populate the scatterlist for dma-buf export and for
mmap operation.

Testcase: default_hugepagesz=2M hugepagesz=2M hugepages=2500 options
were passed to the Host kernel and Qemu was launched with these
relevant options: qemu-system-x86_64 -m 4096m....
-device virtio-gpu-pci,max_outputs=1,blob=true,xres=1920,yres=1080
-display gtk,gl=on
-object memory-backend-memfd,hugetlb=on,id=mem1,size=4096M
-machine memory-backend=mem1

Replacing -display gtk,gl=on with -display gtk,gl=off above would
exercise the mmap handler.

v2: Updated the second patch to manually populate the scatterlist

Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>`
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Cc: Junxiao Chang <junxiao.chang@intel.com>

Vivek Kasireddy (2):
  udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap
  udmabuf: Add back support for mapping hugetlb pages (v2)

 drivers/dma-buf/udmabuf.c | 92 ++++++++++++++++++++++++++++++++-------
 1 file changed, 76 insertions(+), 16 deletions(-)

-- 
2.39.2