[ofa-general] mmap() and ibv_reg_mr() and RDMA

[Joerg Zinke]

On Tue, 22 May 2007 15:19:15 -0700
Roland Dreier <rdreier at cisco.com> wrote:

>  > this area is mapped via the character device and with
>  > the help of remap_pfn_range() into userspace... this works fine i
>  > can access it from userspace and write/read from it:
> 
> I think that's the problem.  remap_pfn_range() sets VM_PFNMAP on the
> vma used to map the pfns.  When ibv_reg_mr() calls into the kernel to
> do the actual mapping, it ends up doing get_user_pages() which fails
> in vm_normal_page() for such a vma.
> 
> I don't immediately see a good way to handle this.
> 

many thanks for your fast answer. i will try to access the memory via
get_user_pages() too instead of mmap'ing it... just the other way
around - should be no problem.

regards,

joerg