[openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation

[Andrew Morton]

Roland Dreier <roland at topspin.com> wrote:
>
>     Andrew> ug.  What stops the memory from leaking if the process
>     Andrew> exits?
> 
>     Andrew> I hope this is a privileged operation?
> 
> I don't think it has to be privileged.  In my implementation, the
> driver keeps a per-process list of registered memory regions and
> unpins/cleans up on process exit.

How does the driver detect process exit?

>     Andrew> It would be better to obtain this memory via a mmap() of
>     Andrew> some special device node, so we can perform appropriate
>     Andrew> permission checking and clean everything up on unclean
>     Andrew> application exit.
> 
> This seems to interact poorly with how applications want to use RDMA,
> ie typically through a library interface such as MPI.  People doing
> HPC don't want to recode their apps to use a new allocator, they just
> want to link to a new MPI library and have the app go fast.

Fair enough.