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Date:   Wed, 20 Mar 2019 12:40:29 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     John Hubbard <jhubbard@nvidia.com>
Cc:     Jerome Glisse <jglisse@redhat.com>, 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>,
        Christopher Lameter <cl@linux.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.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>,
        Tom Talpey <tom@talpey.com>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v4 1/1] mm: introduce put_user_page*(), placeholder
 versions
Message-ID: <20190320094029.ifweqx4wowyyr3wi@kshutemo-mobl1>
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On Tue, Mar 19, 2019 at 12:24:00PM -0700, John Hubbard wrote:
> So, I could be persuaded either way. But given the lack of an visible perf
> effects, and given that this could will get removed anyway because we'll
> likely end up with set_page_dirty() called at GUP time instead...it seems
> like it's probably OK to just leave it as is.

Apart from ugly code generated, other argument might be Spectre-like
attacks on these call. I would rather avoid indirect function calls
whenever possible. And I don't think opencodded versions of these
functions would look much worse.

-- 
 Kirill A. Shutemov