Using ion memory for direct-io

[Zengtao (B)]

Hi 

Currently, the ion mapped to userspace will be forced with VM_IO and VM_PFNMAP flags.
When I use the ion memory to do the direct-io, it will fail when reaching the get_user_pages,

Back to the VM_IO and VM_PFNMAP flag, there two flags are introduced by the remap_pfn_range called 
by the ion_heap_mmap_user.

>From my point of view, all ion memory(cma/vmalloc/system heap) are managed by linux vm, it
is not reasonable to have the VM_IO and VM_PFNMAP flag, but I don't any suitable function
to replace the remap_pfn_range, any suggestions?

Thanks && Regards

Zengtao