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Date:   Wed, 20 Mar 2019 01:01:06 +0000
From:   Christopher Lameter <cl@linux.com>
To:     Dave Chinner <david@fromorbit.com>
cc:     Jerome Glisse <jglisse@redhat.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        john.hubbard@gmail.com, Andrew Morton <akpm@linux-foundation.org>,
        linux-mm@kvack.org, Al Viro <viro@zeniv.linux.org.uk>,
        Christian Benvenuti <benve@cisco.com>,
        Christoph Hellwig <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Dennis Dalessandro <dennis.dalessandro@intel.com>,
        Doug Ledford <dledford@redhat.com>,
        Ira Weiny <ira.weiny@intel.com>, Jan Kara <jack@suse.cz>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@kernel.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Mike Marciniszyn <mike.marciniszyn@intel.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
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        linux-fsdevel@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH v4 1/1] mm: introduce put_user_page*(), placeholder
 versions
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On Wed, 20 Mar 2019, Dave Chinner wrote:

> So the plan for GUP vs writeback so far is "break fsync()"? :)

Well if its an anonymous page and not a file backed page then the
semantics are preserved. Disallow GUP long term pinning (marking stuff like in this
patchset may make that possible) and its clean.