[openib-general] Re: [PATCH 06/16] IB uverbs: memory pinning implementation

[Andrew Morton]

Roland Dreier <rolandd at cisco.com> wrote:
>
> Add support for pinning userspace memory regions and returning a list
> of pages in the region.  This includes tracking pinned memory against
> vm_locked and preventing unprivileged users from exceeding RLIMIT_MEMLOCK.
> 

Can you tell us a bit more about the design ideas here?  What's it doing,
how and why?

We should look at these things and also decide whether some of this should
live in mm/*.

> +int ib_umem_get(struct ib_device *dev, struct ib_umem *mem,
> +		void *addr, size_t size, int write)
> +{
> ...
> +	if (!can_do_mlock())
> +		return -EPERM;
> +
> ...
> +	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {

The capable() test is redundant.