# Re: \[PATCH\] Increase default MLOCK\_LIMIT to 8 MiB

- From: Vlastimil Babka \<hidden\>
- Date: 2021-11-23 22:05:06 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2021/11/1583308
- Thread: https://ratatoskr.run/linux-api/2021/10/1556573/t.md

```text
On 11/23/21 18:00, Jason Gunthorpe wrote:
> 
>> believe what you say and I trust your experience :) So could as well be
>> that on such a "special" (or not so special) systems there should be a
>> way to restrict it to privileged users only.
> 
> At this point RDMA is about as "special" as people running large
> ZONE_MOVABLE systems, and the two are going to start colliding
> heavily. The RDMA VFIO migration driver should be merged soon which
> makes VMs using this stuff finally practical.

How does that work, I see the word migration, so does it cause pages to
be migrated out of ZONE_MOVABLE before they are pinned?
Similarly for io-uring we could be migrating pages to be pinned so that
the end up consolidated close together, and prevent pathologic
situations like in David's reproducer. IIRC that was a idea to do for
long-term pins in general.

> Jason
> 

```