Re: [RESEND PATCH 0/7] Add FOLL_LONGTERM to GUP fast and use it

Andrew Morton
2019-03-19T22:19:30Z

On Sun, 17 Mar 2019 11:34:31 -0700 ira.weiny@intel.com wrote:

> Resending after rebasing to the latest mm tree.
>
> HFI1, qib, and mthca, use get_user_pages_fast() due to it performance
> advantages. These pages can be held for a significant time. But
> get_user_pages_fast() does not protect against mapping FS DAX pages.
>
> Introduce FOLL_LONGTERM and use this flag in get_user_pages_fast() which
> retains the performance while also adding the FS DAX checks. XDP has also
> shown interest in using this functionality.[1]
>
> In addition we change get_user_pages() to use the new FOLL_LONGTERM flag and
> remove the specialized get_user_pages_longterm call.

It would be helpful to include your response to Christoph's question
(http://lkml.kernel.org/r/20190220180255.GA12020@iweiny-DESK2.sc.intel.com)
in the changelog. Because if one person was wondering about this,
others will likely do so.

We have no record of acks or reviewed-by's. At least one was missed
(http://lkml.kernel.org/r/CAOg9mSTTcD-9bCSDfC0WRYqfVrNB4TwOzL0c4+6QXi-N_Y43Vw@mail.gmail.com),
but that is very very partial.

This patchset is fairly DAX-centered, but Dan wasn't cc'ed!

So ho hum. I'll scoop them up and shall make the above changes to the
[1/n] changelog, but we still have some work to do.