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Date: Tue, 19 Mar 2019 15:19:30 -0700
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RESEND PATCH 0/7] Add FOLL_LONGTERM to GUP fast and use it
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To: ira.weiny@intel.com
Cc: John Hubbard <jhubbard@nvidia.com>, Michal Hocko <mhocko@suse.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Jason Gunthorpe <jgg@ziepe.ca>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, "David S. Miller" <davem@davemloft.net>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Rich Felker <dalias@libc.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Ralf Baechle <ralf@linux-mips.org>, James Hogan <jhogan@kernel.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, Dan Williams <dan.j.williams@intel.com>
List-ID: <linux-s390.vger.kernel.org>

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.