ibv_reg_mr and mmap'ed memory

[Jörn Schumacher <jorn.schumacher@xxxxxxx>]

Hi all,

I am trying to register an mmap'ed memory region as send buffer using 
ibv_reg_mr (via a libfabric call).

The address is a virtual address that has been mmap'ed from a kernel 
address in a custom kernel driver. The mapping uses remap_pfn_range:


   vma->vm_flags |= VM_DONTEXPAND;
   vma->vm_flags |= VM_DONTDUMP;
   vma->vm_flags |= VM_LOCKED;
   remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size, 
vma->vm_page_prot)


The ibv_reg_mr call fails with -22 (Invalid argument). The call succeeds 
if I replace the buffer with a simple malloc'ed buffer.

Why would this not work with mmap'ed memory? Is there a way of mmap'ing 
the kernel address to user space that would allow the memory registration?

Thanks!

Cheers,
Jörn