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Date:   Fri, 7 Feb 2020 16:18:06 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     John Hubbard <jhubbard@nvidia.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Chinner <david@fromorbit.com>,
        Ira Weiny <ira.weiny@intel.com>, Jan Kara <jack@suse.cz>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Jonathan Corbet <corbet@lwn.net>,
        =?utf-8?B?SsOpcsO0bWU=?= Glisse <jglisse@redhat.com>,
        Michal Hocko <mhocko@suse.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Shuah Khan <shuah@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Matthew Wilcox <willy@infradead.org>,
        linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org,
        linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 04/12] mm: introduce page_ref_sub_return()
Message-ID: <20200207131806.xwnhxomxgt3hoqcc@box>
References: <20200207033735.308000-1-jhubbard@nvidia.com>
 <20200207033735.308000-5-jhubbard@nvidia.com>
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On Thu, Feb 06, 2020 at 07:37:27PM -0800, John Hubbard wrote:
> An upcoming patch requires subtracting a large chunk of refcounts from
> a page, and checking what the resulting refcount is. This is a little
> different than the usual "check for zero refcount" that many of the
> page ref functions already do. However, it is similar to a few other
> routines that (like this one) are generally useful for things such as
> 1-based refcounting.
> 
> Add page_ref_sub_return(), that subtracts a chunk of refcounts
> atomically, and returns an atomic snapshot of the result.
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov