Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA

From: John Hubbard
Date: Tue Feb 12 2019 - 21:58:27 EST

On 2/12/19 8:39 AM, Christopher Lameter wrote:
> On Mon, 11 Feb 2019, John Hubbard wrote:
>> But anyway, Jan's proposal a bit earlier today [1] is finally sinking into
>> my head--if we actually go that way, and prevent the caller from setting up
>> a problematic gup pin in the first place, then that may make this point sort
>> of moot.
> Ok well can be document how we think it would work somewhere? Long term
> mapping a page cache page could a problem and we need to explain that
> somewhere.

Yes, once the dust settles, I think Documentation/vm/get_user_pages.rst is the
right place. I started to create that file, but someone observed that my initial
content was entirely backward-looking (described the original problem, instead
of describing how the new system would work). So I'll use this opportunity for
a do-over. :)

John Hubbard